RNA recognition motif;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 755566165   341 VLYLKNLSPRVKERDLISLFARFqekkGPPIQFRMM----TGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVI 413
Cdd:smart00360   1 TLFVGNLPPDTTEEELRELFSKF----GKVESVRLVrdkeTGKSKGFAFVEFESEEDAEKALEALNGKELDGRPLKV 73

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 755566165  342 LYLKNLSPRVKERDLISLFARFqekkGPPIQFRMM---TGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKIL 411
Cdd:pfam00076   1 LFVGNLPPDTTEEDLKDLFSKF----GPIKSIRLVrdeTGRSKGFAFVEFEDEEDAEKAIEALNGKELGGREL 69

RNA recognition motif 1 (RRM1) found in the U1A/U2B"/SNF protein family; This subfamily corresponds to the RRM1 of U1A/U2B"/SNF protein family which contains Drosophila sex determination protein SNF and its two mammalian counterparts, U1 small nuclear ribonucleoprotein A (U1 snRNP A or U1-A or U1A) and U2 small nuclear ribonucleoprotein B" (U2 snRNP B" or U2B"), all of which consist of two RNA recognition motifs (RRMs), connected by a variable, flexible linker. SNF is an RNA-binding protein found in the U1 and U2 snRNPs of Drosophila where it is essential in sex determination and possesses a novel dual RNA binding specificity. SNF binds with high affinity to both Drosophila U1 snRNA stem-loop II (SLII) and U2 snRNA stem-loop IV (SLIV). It can also bind to poly(U) RNA tracts flanking the alternatively spliced Sex-lethal (Sxl) exon, as does Drosophila Sex-lethal protein (SXL). U1A is an RNA-binding protein associated with the U1 snRNP, a small RNA-protein complex involved in pre-mRNA splicing. U1A binds with high affinity and specificity to stem-loop II (SLII) of U1 snRNA. It is predominantly a nuclear protein that shuttles between the nucleus and the cytoplasm independently of interactions with U1 snRNA. Moreover, U1A may be involved in RNA 3'-end processing, specifically cleavage, splicing and polyadenylation, through interacting with a large number of non-snRNP proteins. U2B", initially identified to bind to stem-loop IV (SLIV) at the 3' end of U2 snRNA, is a unique protein that comprises of the U2 snRNP. Additional research indicates U2B" binds to U1 snRNA stem-loop II (SLII) as well and shows no preference for SLIV or SLII on the basis of binding affinity. Moreover, U2B" does not require an auxiliary protein for binding to RNA, and its nuclear transport is independent of U2 snRNA binding.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165 342 LYLKNLSPRVKERDLI-SLFARFQeKKGPPIQFRMM-TGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAK 417
Cdd:cd12246    2 LYINNLNEKIKKDELKrSLYALFS-QFGPVLDIVASkSLKMRGQAFVVFKDVESATNALRALQGFPFYGKPMRIQYAK 78

RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 755566165 342 LYLKNLSPRVKERDLISLFARFqekkGPPIQFRMMT---GRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIE 414
Cdd:cd00590    1 LFVGNLPPDTTEEDLRELFSKF----GEVVSVRIVRdrdGKSKGFAFVEFESPEDAEKALEALNGTELGGRPLKVS 72

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 755566165  342 LYLKNLSPRVKERDLISLFARFqekkGPPIQFRMM---TGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKIL 411
Cdd:pfam00076   1 LFVGNLPPDTTEEDLKDLFSKF----GPIKSIRLVrdeTGRSKGFAFVEFEDEEDAEKAIEALNGKELGGREL 69

RNA recognition motif (RRM) found in serine/arginine-rich splicing factor SRSF10, SRSF12 and similar proteins; This subfamily corresponds to the RRM of SRSF10 and SRSF12. SRSF10, also termed 40 kDa SR-repressor protein (SRrp40), or FUS-interacting serine-arginine-rich protein 1 (FUSIP1), or splicing factor SRp38, or splicing factor, arginine/serine-rich 13A (SFRS13A), or TLS-associated protein with Ser-Arg repeats (TASR). It is a serine-arginine (SR) protein that acts as a potent and general splicing repressor when dephosphorylated. It mediates global inhibition of splicing both in M phase of the cell cycle and in response to heat shock. SRSF10 emerges as a modulator of cholesterol homeostasis through the regulation of low-density lipoprotein receptor (LDLR) splicing efficiency. It also regulates cardiac-specific alternative splicing of triadin pre-mRNA and is required for proper Ca2+ handling during embryonic heart development. In contrast, the phosphorylated SRSF10 functions as a sequence-specific splicing activator in the presence of a nuclear cofactor. It activates distal alternative 5' splice site of adenovirus E1A pre-mRNA in vivo. Moreover, SRSF10 strengthens pre-mRNA recognition by U1 and U2 snRNPs. SRSF10 localizes to the nuclear speckles and can shuttle between nucleus and cytoplasm. SRSF12, also termed 35 kDa SR repressor protein (SRrp35), or splicing factor, arginine/serine-rich 13B (SFRS13B), or splicing factor, arginine/serine-rich 19 (SFRS19), is a serine/arginine (SR) protein-like alternative splicing regulator that antagonizes authentic SR proteins in the modulation of alternative 5' splice site choice. For instance, it activates distal alternative 5' splice site of the adenovirus E1A pre-mRNA in vivo. Both, SRSF10 and SRSF12, contain a single N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), followed by a C-terminal RS domain rich in serine-arginine dipeptides.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 342 LYLKNLSPRVKERDLISLFARFqekkGP------PIQFRmmTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEF 415
Cdd:cd12312    3 LFVRNVADDTRPDDLRREFGRY----GPivdvyiPLDFY--TRRPRGFAYIQFEDVRDAEDALYYLDRTRFLGREIEIQF 76

                 ..
gi 755566165 416 AK 417
Cdd:cd12312   77 AQ 78

RNA recognition motif 1 (RRM1) found in Drosophila melanogaster sex determination protein SNF and similar proteins; This subgroup corresponds to the RRM1 of SNF (Sans fille), also termed U1 small nuclear ribonucleoprotein A (U1 snRNP A or U1-A or U1A), an RNA-binding protein found in the U1 and U2 snRNPs of Drosophila. It is essential in Drosophila sex determination and possesses a novel dual RNA binding specificity. SNF binds with high affinity to both Drosophila U1 snRNA stem-loop II (SLII) and U2 snRNA stem-loop IV (SLIV). It can also bind to poly(U) RNA tracts flanking the alternatively spliced Sex-lethal (Sxl) exon, as does Drosophila Sex-lethal protein (SXL). SNF contains two RNA recognition motifs (RRMs); it can self-associate through RRM1, and each RRM can recognize poly(U) RNA binding independently.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 338 PNKVLYLKNLSPRVKERDLI-SLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFA 416
Cdd:cd12476    5 PNQTIYINNLNEKVKKEELKkSLYAIFSQFGQILDIVALKTLKMRGQAFVIFKDISSATNALRSMQGFPFYDKPMRIAYS 84

                 .
gi 755566165 417 K 417
Cdd:cd12476   85 K 85

RNA recognition motif 1 (RRM1) found in the VICKZ family proteins; Thid subfamily corresponds to the RRM1 of IGF2BPs (or IMPs) found in the VICKZ family that have been implicated in the post-transcriptional regulation of several different RNAs and in subcytoplasmic localization of mRNAs during embryogenesis. IGF2BPs are composed of two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and four hnRNP K homology (KH) domains.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 755566165 342 LYLKNLSPRVKERDLISLFarfQEKKGPPIQFRMMTGrmrGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAKSKK 420
Cdd:cd12358    1 LYIGNLSSDVNESDLRQLF---EEHKIPVSSVLVKKG---GYAFVDCPDQSWADKAIEKLNGKILQGKVIEVEHSVPKK 73

RNA recognition motif 1 in U2 small nuclear ribonucleoprotein B" (U2B") and similar proteins; This subgroup corresponds to the RRM1 of U2B" (also termed U2 snRNP B") a unique protein that comprises the U2 snRNP. It was initially identified as binding to stem-loop IV (SLIV) at the 3' end of U2 snRNA. Additional research indicates U2B" binds to U1 snRNA stem-loop II (SLII) as well and shows no preference for SLIV or SLII on the basis of binding affinity. U2B" does not require an auxiliary protein for binding to RNA. In addition, the nuclear transport of U2B" is independent of U2 snRNA binding. U2B" contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). It also contains a nuclear localization signal (NLS) in the central domain. However, nuclear import of U2B'' does not depend on this NLS. The N-terminal RRM is sufficient to direct U2B" to the nucleus.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 339 NKVLYLKNLSPRVKERDLI-SLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAK 417
Cdd:cd12478    1 NHTIYINNINDKIKKEELKrSLYALFSQFGHVVDIVALKTMKMRGQAFVIFKELSSATNALRQLQGFPFYGKPMRIQYAK 80

                 .
gi 755566165 418 S 418
Cdd:cd12478   81 T 81

RNA recognition motif 1 (RRM1) found in vertebrate insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2); This subgroup corresponds to the RRM1 of IGF2BP2 (IGF2 mRNA-binding protein 2 or IMP-2), also termed hepatocellular carcinoma autoantigen p62, or VICKZ family member 2, which is a ubiquitously expressed RNA-binding protein involved in the stimulation of insulin action. It is predominantly nuclear. SNPs in IGF2BP2 gene are implicated in susceptibility to type 2 diabetes. IGF2BP2 plays an important role in cellular motility; it regulates the expression of PINCH-2, an important mediator of cell adhesion and motility, and MURF-3, a microtubule-stabilizing protein, through direct binding to their mRNAs. IGF2BP2 may be involved in the regulation of mRNA stability through the interaction with the AU-rich element-binding factor AUF1. IGF2BP2 binds initially to nascent beta-actin transcripts and facilitates the subsequent binding of the shuttling IGF2BP1. IGF2BP2 contains four hnRNP K-homology (KH) domains, two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a RGG RNA-binding domain.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 339 NKvLYLKNLSPRVKERDLISLFArfqEKKGPpiqfrmMTGRM---RGQAFLTFPNKDIAWQALHQING-YKLYGKILVIE 414
Cdd:cd12626    2 NK-LYIGNLSPAVTAEDLRQLFG---DRKLP------LTGQVllkSGYAFVDYPDQNWAIRAIETLSGkVELHGKVMEVD 71

                 ....*.
gi 755566165 415 FAKSKK 420
Cdd:cd12626   72 YSVPKK 77

RNA recognition motif 3 (RRM3) found in the Hu proteins family; This subfamily corresponds to the RRM3 of the Hu proteins family which represent a group of RNA-binding proteins involved in diverse biological processes. Since the Hu proteins share high homology with the Drosophila embryonic lethal abnormal vision (ELAV) protein, the Hu family is sometimes referred to as the ELAV family. Drosophila ELAV is exclusively expressed in neurons and is required for the correct differentiation and survival of neurons in flies. The neuronal members of the Hu family include Hu-antigen B (HuB or ELAV-2 or Hel-N1), Hu-antigen C (HuC or ELAV-3 or PLE21), and Hu-antigen D (HuD or ELAV-4), which play important roles in neuronal differentiation, plasticity and memory. HuB is also expressed in gonads. Hu-antigen R (HuR or ELAV-1 or HuA) is the ubiquitously expressed Hu family member. It has a variety of biological functions mostly related to the regulation of cellular response to DNA damage and other types of stress. Hu proteins perform their cytoplasmic and nuclear molecular functions by coordinately regulating functionally related mRNAs. In the cytoplasm, Hu proteins recognize and bind to AU-rich RNA elements (AREs) in the 3' untranslated regions (UTRs) of certain target mRNAs, such as GAP-43, vascular epithelial growth factor (VEGF), the glucose transporter GLUT1, eotaxin and c-fos, and stabilize those ARE-containing mRNAs. They also bind and regulate the translation of some target mRNAs, such as neurofilament M, GLUT1, and p27. In the nucleus, Hu proteins function as regulators of polyadenylation and alternative splicing. Each Hu protein contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an ARE. RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEF 415
Cdd:cd12377    2 IFVYNLAPDADESLLWQLFGPFGAVQNVKIIRDFTTNKCKGYGFVTMTNYDEAAVAIASLNGYRLGGRVLQVSF 75

RNA recognition motif (RRM) found in transformer-2 protein homolog TRA2-alpha, TRA2-beta and similar proteins; This subfamily corresponds to the RRM of two mammalian homologs of Drosophila transformer-2 (Tra2), TRA2-alpha, TRA2-beta (also termed SFRS10), and similar proteins found in eukaryotes. TRA2-alpha is a 40-kDa serine/arginine-rich (SR) protein that specifically binds to gonadotropin-releasing hormone (GnRH) exonic splicing enhancer on exon 4 (ESE4) and is necessary for enhanced GnRH pre-mRNA splicing. It strongly stimulates GnRH intron A excision in a dose-dependent manner. In addition, TRA2-alpha can interact with either 9G8 or SRp30c, which may also be crucial for ESE-dependent GnRH pre-mRNA splicing. TRA2-beta is a serine/arginine-rich (SR) protein that controls the pre-mRNA alternative splicing of the calcitonin/calcitonin gene-related peptide (CGRP), the survival motor neuron 1 (SMN1) protein and the tau protein. Both, TRA2-alpha and TRA2-beta, contains a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), flanked by the N- and C-terminal arginine/serine (RS)-rich regions.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165 339 NKVLYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFA 416
Cdd:cd12363    1 SRCLGVFGLSLYTTERDLREVFSRYGPIEKVQVVYDQQTGRSRGFGFVYFESVEDAKEAKERLNGQEIDGRRIRVDYS 78

RNA recognition motif 1 (RRM1) found in plant polypyrimidine tract-binding protein homolog 1 and 2 (PTBPH1 and PTBPH2); This subfamily corresponds to the RRM1 of PTBPH1 and PTBPH2. Although their biological roles remain unclear, PTBPH1 and PTBPH2 show significant sequence similarity to polypyrimidine tract binding protein (PTB) that is an important negative regulator of alternative splicing in mammalian cells and also functions at several other aspects of mRNA metabolism, including mRNA localization, stabilization, polyadenylation, and translation. Both, PTBPH1 and PTBPH2, contain three RNA recognition motifs (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 755566165 338 PNKVLYLKNLSPRVKERDLISLFARFqekkGPPIQFRMMTGRMRGQAFLTFPNKDiawQALHQINGY 404
Cdd:cd12686    1 PSKVLHLRNLPWECTEEELIELCKPF----GTVVNTKCNVGANKNQAFVEFADLN---QAISMVSYY 60

RNA recognition motif 1 (RRM1) found in vertebrate U1 small nuclear ribonucleoprotein A (U1A); This subgroup corresponds to the RRM1 of U1A (also termed U1 snRNP A or U1-A), an RNA-binding protein associated with the U1 snRNP, a small RNA-protein complex involved in pre-mRNA splicing. U1A binds with high affinity and specificity to stem-loop II (SLII) of U1 snRNA. It is predominantly a nuclear protein and it also shuttles between the nucleus and the cytoplasm independently of interactions with U1 snRNA. U1A may be involved in RNA 3'-end processing, specifically cleavage, splicing and polyadenylation, through interacting with a large number of non-snRNP proteins, including polypyrimidine tract binding protein (PTB), polypyrimidine-tract binding protein-associated factor (PSF), and non-POU-domain-containing, octamer-binding (NONO), DEAD (Asp-Glu-Ala-Asp) box polypeptide 5 (DDX5). It also binds to a flavivirus NS5 protein and plays an important role in virus replication. U1A contains two RNA recognition motifs (RRMs); the N-terminal RRM (RRM1) binds tightly and specifically to the U1 snRNA SLII and its own 3'-UTR, while in contrast, the C-terminal RRM (RRM2) does not appear to associate with any RNA and may be free to bind other proteins. U1A also contains a proline-rich region, and a nuclear localization signal (NLS) in the central domain that is responsible for its nuclear import.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 338 PNKVLYLKNLSPRVKE----RDLISLFARFQEKKGPPIQFRMmtgRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVI 413
Cdd:cd12477    2 PNHTIYINNLNEKIKKdelkKSLHAIFSRFGQILDILVSRSL---KMRGQAFVIFKEVSSATNALRSMQGFPFYDKPMRI 78

                 ....*...
gi 755566165 414 EFAKSKKQ 421
Cdd:cd12477   79 QYAKTDSD 86

RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein R (hnRNP R) and similar proteins; This subfamily corresponds to the RRM1 in hnRNP R, hnRNP Q, APOBEC-1 complementation factor (ACF), and dead end protein homolog 1 (DND1). hnRNP R is a ubiquitously expressed nuclear RNA-binding protein that specifically binds mRNAs with a preference for poly(U) stretches. It has been implicated in mRNA processing and mRNA transport, and also acts as a regulator to modify binding to ribosomes and RNA translation. hnRNP Q is also a ubiquitously expressed nuclear RNA-binding protein. It has been identified as a component of the spliceosome complex, as well as a component of the apobec-1 editosome, and has been implicated in the regulation of specific mRNA transport. ACF is an RNA-binding subunit of a core complex that interacts with apoB mRNA to facilitate C to U RNA editing. It may also act as an apoB mRNA recognition factor and chaperone, and play a key role in cell growth and differentiation. DND1 is essential for maintaining viable germ cells in vertebrates. It interacts with the 3'-untranslated region (3'-UTR) of multiple messenger RNAs (mRNAs) and prevents micro-RNA (miRNA) mediated repression of mRNA. This family also includes two functionally unknown RNA-binding proteins, RBM46 and RBM47. All members in this family, except for DND1, contain three conserved RNA recognition motifs (RRMs); DND1 harbors only two RRMs.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 755566165 342 LYLKNLsPR-VKERDLISLFarfqEKKGPPIQFRMM---TGRMRGQAFLTFPNKDIAWQALHQINGYKL 406
Cdd:cd12249    4 VFVGKI-PRdVFEDELVPLF----EKCGKIYELRLMmdfSGLNRGYAFVTYTNKEAAQRAVKTLNNYEI 67

RNA recognition motif 2 (RRM2) found in vertebrate RNA-binding protein RBM23, RBM39 and similar proteins; This subfamily corresponds to the RRM2 of RBM39 (also termed HCC1), a nuclear autoantigen that contains an N-terminal arginine/serine rich (RS) motif and three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). An octapeptide sequence called the RS-ERK motif is repeated six times in the RS region of RBM39. Although the cellular function of RBM23 remains unclear, it shows high sequence homology to RBM39 and contains two RRMs. It may possibly function as a pre-mRNA splicing factor.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGK 409
Cdd:cd12284    1 LYVGSLHFNITEDMLRGIFEPFGKIEFVQLQKDPETGRSKGYGFIQFRDAEDAKKALEQLNGFELAGR 68

RNA recognition motif 3 (RRM3) found in vertebrate Hu-antigen D (HuD); This subgroup corresponds to the RRM3 of HuD, also termed ELAV-like protein 4 (ELAV-4), or paraneoplastic encephalomyelitis antigen HuD, one of the neuronal members of the Hu family. The neuronal Hu proteins play important roles in neuronal differentiation, plasticity and memory. HuD has been implicated in various aspects of neuronal function, such as the commitment and differentiation of neuronal precursors as well as synaptic remodeling in mature neurons. HuD also functions as an important regulator of mRNA expression in neurons by interacting with AU-rich RNA element (ARE) and stabilizing multiple transcripts. Moreover, HuD regulates the nuclear processing/stability of N-myc pre-mRNA in neuroblastoma cells. And it also regulates the neurite elongation and morphological differentiation. HuD specifically bound poly(A) RNA. Like other Hu proteins, HuD contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an ARE. RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAKSKKQ 421
Cdd:cd12656    6 IFVYNLSPDSDESVLWQLFGPFGAVNNVKVIRDFNTNKCKGFGFVTMTNYDEAAMAIASLNGYRLGDRVLQVSFKTNKTH 85

                 .
gi 755566165 422 Q 422
Cdd:cd12656   86 K 86

RNA recognition motif (RRM) found in pre-mRNA branch site protein p14 (SF3B14) and similar proteins; This subfamily corresponds to the RRM of SF3B14 (also termed p14), a 14 kDa protein subunit of SF3B which is a multiprotein complex that is an integral part of the U2 small nuclear ribonucleoprotein (snRNP) and the U11/U12 di-snRNP. SF3B is essential for the accurate excision of introns from pre-messenger RNA and has been involved in the recognition of the pre-mRNA's branch site within the major and minor spliceosomes. SF3B14 associates directly with another SF3B subunit called SF3B155. It is also present in both U2- and U12-dependent spliceosomes and may contribute to branch site positioning in both the major and minor spliceosome. Moreover, SF3B14 interacts directly with the pre-mRNA branch adenosine early in spliceosome assembly and within the fully assembled spliceosome. SF3B14 contains one well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 755566165 339 NKVLYLKNLSPRVKERDLISLFARFqekkGPPIQFRM-MTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVI 413
Cdd:cd12241    2 NRILYVRNLPYKISSEELYDLFGKY----GAIRQIRIgNTKETRGTAFVVYEDIFDAKNACDHLSGFNVCNRYLVV 73

RNA recognition motif 2 (RRM2) found in yeast nuclear and cytoplasmic polyadenylated RNA-binding protein PUB1 and similar proteins; This subgroup corresponds to the RRM2 of yeast protein PUB1, also termed ARS consensus-binding protein ACBP-60, or poly uridylate-binding protein, or poly(U)-binding protein. PUB1 has been identified as both, a heterogeneous nuclear RNA-binding protein (hnRNP) and a cytoplasmic mRNA-binding protein (mRNP), which may be stably bound to a translationally inactive subpopulation of mRNAs within the cytoplasm. It is distributed in both, the nucleus and the cytoplasm, and binds to poly(A)+ RNA (mRNA or pre-mRNA). Although it is one of the major cellular proteins cross-linked by UV light to polyadenylated RNAs in vivo, PUB1 is nonessential for cell growth in yeast. PUB1 also binds to T-rich single stranded DNA (ssDNA). However, there is no strong evidence implicating PUB1 in the mechanism of DNA replication. PUB1 contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a GAR motif (glycine and arginine rich stretch) that is located between RRM2 and RRM3.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFA 416
Cdd:cd12619    4 IFVGDLSPEVTDAALFNAFSDFPSCSDARVMWDQKTGRSRGYGFVSFRSQQDAQNAINSMNGKWLGSRPIRCNWA 78

RNA recognition motif 3 (RRM3) found in heterogeneous nuclear ribonucleoprotein R (hnRNP R) and similar proteins; This subfamily corresponds to the RRM3 in hnRNP R, hnRNP Q, and APOBEC-1 complementation factor (ACF). hnRNP R is a ubiquitously expressed nuclear RNA-binding protein that specifically bind mRNAs with a preference for poly(U) stretches and has been implicated in mRNA processing and mRNA transport, and also acts as a regulator to modify binding to ribosomes and RNA translation. hnRNP Q is also a ubiquitously expressed nuclear RNA-binding protein. It has been identified as a component of the spliceosome complex, as well as a component of the apobec-1 editosome, and has been implicated in the regulation of specific mRNA transport. ACF is an RNA-binding subunit of a core complex that interacts with apoB mRNA to facilitate C to U RNA editing. It may also act as an apoB mRNA recognition factor and chaperone and play a key role in cell growth and differentiation. This family also includes two functionally unknown RNA-binding proteins, RBM46 and RBM47. All members contain three conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 340 KVLYLKNLSPRVKERDLISLFARFQE----KKgppiqfrmmtgrMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEF 415
Cdd:cd12251    2 KVLYVRNLMLSTTEEKLRELFSEYGKvervKK------------IKDYAFVHFEERDDAVKAMEEMNGKELEGSEIEVSL 69

                 ..
gi 755566165 416 AK 417
Cdd:cd12251   70 AK 71

RNA recognition motif (RRM) found in U2-associated protein SR140 and similar proteins; This subgroup corresponds to the RRM of SR140 (also termed U2 snRNP-associated SURP motif-containing protein orU2SURP, or 140 kDa Ser/Arg-rich domain protein) which is a putative splicing factor mainly found in higher eukaryotes. Although it is initially identified as one of the 17S U2 snRNP-associated proteins, the molecular and physiological function of SR140 remains unclear. SR140 contains an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), a SWAP/SURP domain that is found in a number of pre-mRNA splicing factors in the middle region, and a C-terminal arginine/serine-rich domain (RS domain).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 342 LYLKNLSPRVKERDLISLFARFqekkGPPIQFRMM-------TGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIE 414
Cdd:cd12223    4 LYVGNLPPSVTEEVLLREFGRF----GPLASVKIMwprteeeRRRNRNCGFVAFMSRADAERAMRELNGKDVMGYELKLG 79

                 ....
gi 755566165 415 FAKS 418
Cdd:cd12223   80 WGKA 83

ELAV/HuD family splicing factor; This model describes the ELAV/HuD subfamily of splicing factors found in metazoa. HuD stands for the human paraneoplastic encephalomyelitis antigen D of which there are 4 variants in human. ELAV stnds for the Drosophila Embryonic lethal abnormal visual protein. ELAV-like splicing factors are also known in human as HuB (ELAV-like protein 2), HuC (ELAV-like protein 3, Paraneoplastic cerebellar degeneration-associated antigen) and HuR (ELAV-like protein 1). These genes are most closely related to the sex-lethal subfamily of splicing factors found in Dipteran insects (TIGR01659). These proteins contain 3 RNA-recognition motifs (rrm: pfam00076).

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165  342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAKSK 419
Cdd:TIGR01661 272 IFVYNLSPDTDETVLWQLFGPFGAVQNVKIIRDLTTNQCKGYGFVSMTNYDEAAMAILSLNGYTLGNRVLQVSFKTNK 349

heterogeneous nuclear ribonucleoprotein R, Q family; Sequences in this subfamily include the human heterogeneous nuclear ribonucleoproteins (hnRNP) R, Q, and APOBEC-1 complementation factor (aka APOBEC-1 stimulating protein). These proteins contain three RNA recognition domains (rrm: pfam00076) and a somewhat variable C-terminal domain.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165  349 PR-VKERDLISLFarfqEKKGPPIQFRMM---TGRMRGQAFLTFPNKDIAWQALHQINGYKLY-GKIL 411
Cdd:TIGR01648  67 PRdLYEDELVPLF----EKAGPIYELRLMmdfSGQNRGYAFVTFCGKEEAKEAVKLLNNYEIRpGRLL 130

RNA recognition motif 3 (RRM3) found in yeast nucleolar protein 4 (Nop4p) and similar proteins; This subgroup corresponds to the RRM3 of Nop4p (also known as Nop77p), encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQ 400
Cdd:cd12676    4 LFVRNLPFDATEDELYSHFSQFGPLKYARVVKDPATGRSKGTAFVKFKNKEDADNCLSA 62

RNA recognition motif 1 (RRM1) found in granule-associated RNA binding proteins p40-TIA-1 and TIAR; This subfamily corresponds to the RRM1 of nucleolysin TIA-1 isoform p40 (p40-TIA-1 or TIA-1) and nucleolysin TIA-1-related protein (TIAR), both of which are granule-associated RNA binding proteins involved in inducing apoptosis in cytotoxic lymphocyte (CTL) target cells. TIA-1 and TIAR share high sequence similarity. They are expressed in a wide variety of cell types. TIA-1 can be phosphorylated by a serine/threonine kinase that is activated during Fas-mediated apoptosis.TIAR is mainly localized in the nucleus of hematopoietic and nonhematopoietic cells. It is translocated from the nucleus to the cytoplasm in response to exogenous triggers of apoptosis. Both, TIA-1 and TIAR, bind specifically to poly(A) but not to poly(C) homopolymers. They are composed of three N-terminal highly homologous RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a glutamine-rich C-terminal auxiliary domain containing a lysosome-targeting motif. TIA-1 and TIAR interact with RNAs containing short stretches of uridylates and their RRM2 can mediate the specific binding to uridylate-rich RNAs. The C-terminal auxiliary domain may be responsible for interacting with other proteins. In addition, TIA-1 and TIAR share a potential serine protease-cleavage site (Phe-Val-Arg) localized at the junction between their RNA binding domains and their C-terminal auxiliary domains.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 755566165 342 LYLKNLSPRVKERDLISLFARFqekkGPPIQFRMMT--GRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFA 416
Cdd:cd12352    1 LYVGNLDRQVTEDLILQLFSQI----GPCKSCKMITehGGNDPYCFVEFYEHNHAAAALQAMNGRKILGKEVKVNWA 73

RNA recognition motif (RRM) found in cyclophilin-33 (Cyp33) and similar proteins; This subfamily corresponds to the RRM of Cyp33, also termed peptidyl-prolyl cis-trans isomerase E (PPIase E), or cyclophilin E, or rotamase E. Cyp33 is a nuclear RNA-binding cyclophilin with an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal PPIase domain. Cyp33 possesses RNA-binding activity and preferentially binds to polyribonucleotide polyA and polyU, but hardly to polyG and polyC. It binds specifically to mRNA, which can stimulate its PPIase activity. Moreover, Cyp33 interacts with the third plant homeodomain (PHD3) zinc finger cassette of the mixed lineage leukemia (MLL) proto-oncoprotein and a poly-A RNA sequence through its RRM domain. It further mediates downregulation of the expression of MLL target genes HOXC8, HOXA9, CDKN1B, and C-MYC, in a proline isomerase-dependent manner. Cyp33 also possesses a PPIase activity that catalyzes cis-trans isomerization of the peptide bond preceding a proline, which has been implicated in the stimulation of folding and conformational changes in folded and unfolded proteins. The PPIase activity can be inhibited by the immunosuppressive drug cyclosporin A.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFA 416
Cdd:cd12347    1 LYVGGLAEEVDEKVLHAAFIPFGDIVDIQIPLDYETEKHRGFAFVEFEEAEDAAAAIDNMNESELFGRTIRVNLA 75

RNA recognition motif (RRM) found in cleavage stimulation factor subunit 2 (CSTF2), cleavage stimulation factor subunit 2 tau variant (CSTF2T) and similar proteins; This subgroup corresponds to the RRM domain of CSTF2, its tau variant and eukaryotic homologs. CSTF2, also termed cleavage stimulation factor 64 kDa subunit (CstF64), is the vertebrate conterpart of yeast mRNA 3'-end-processing protein RNA15. It is expressed in all somatic tissues and is one of three cleavage stimulatory factor (CstF) subunits required for polyadenylation. CstF64 contains an N-terminal RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), a CstF77-binding domain, a repeated MEARA helical region and a conserved C-terminal domain reported to bind the transcription factor PC-4. During polyadenylation, CstF interacts with the pre-mRNA through the RRM of CstF64 at U- or GU-rich sequences within 10 to 30 nucleotides downstream of the cleavage site. CSTF2T, also termed tauCstF64, is a paralog of the X-linked cleavage stimulation factor CstF64 protein that supports polyadenylation in most somatic cells. It is expressed during meiosis and subsequent haploid differentiation in a more limited set of tissues and cell types, largely in meiotic and postmeiotic male germ cells, and to a lesser extent in brain. The loss of CSTF2T will cause male infertility, as it is necessary for spermatogenesis and fertilization. Moreover, CSTF2T is required for expression of genes involved in morphological differentiation of spermatids, as well as for genes having products that function during interaction of motile spermatozoa with eggs. It promotes germ cell-specific patterns of polyadenylation by using its RRM to bind to different sequence elements downstream of polyadenylation sites than does CstF64.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 755566165 342 LYLKNLSPRVKERDLISLFArfqeKKGPPIQFRMM----TGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAK 417
Cdd:cd12671    9 VFVGNIPYEATEEQLKDIFS----EVGPVVSFRLVydreTGKPKGYGFCEYQDQETALSAMRNLNGYELNGRALRVDNAA 84

                 .
gi 755566165 418 S 418
Cdd:cd12671   85 S 85

RNA recognition motif (RRM) found in THO complex subunit 4 (THOC4) and similar proteins; This subgroup corresponds to the RRM of THOC4, also termed transcriptional coactivator Aly/REF, or ally of AML-1 and LEF-1, or bZIP-enhancing factor BEF, an mRNA transporter protein with a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It is involved in RNA transportation from the nucleus. THOC4 was initially identified as a transcription coactivator of LEF-1 and AML-1 for the TCRalpha enhancer function. In addition, THOC4 specifically binds to rhesus (RH) promoter in erythroid. It might be a novel transcription cofactor for erythroid-specific genes.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMmTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEF 415
Cdd:cd12680    3 LLVSNLDFGVSDADIKELFAEFGTLKKAAVHYDR-SGRSLGTAEVVFERRADALKAMKQYNGVPLDGRPMKIQL 75

RNA recognition motif 2 (RRM2) found in heterogeneous nuclear ribonucleoprotein A0 (hnRNP A0) and similar proteins; This subgroup corresponds to the RRM2 of hnRNP A0, a low abundance hnRNP protein that has been implicated in mRNA stability in mammalian cells. It has been identified as the substrate for MAPKAP-K2 and may be involved in the lipopolysaccharide (LPS)-induced post-transcriptional regulation of tumor necrosis factor-alpha (TNF-alpha), cyclooxygenase 2 (COX-2) and macrophage inflammatory protein 2 (MIP-2). hnRNP A0 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQA----LHQINGYK 405
Cdd:cd12579    2 LFVGGLKGDVGEGDLVEHFSQFGTVEKVEVIADKDTGKKRGFGFVYFEDHDSADKAavvkFHSINGHR 69

RNA recognition motif 3 (RRM3) found in vertebrate nucleolin; This subfamily corresponds to the RRM3 of ubiquitously expressed protein nucleolin, also termed protein C23, is a multifunctional major nucleolar phosphoprotein that has been implicated in various metabolic processes, such as ribosome biogenesis, cytokinesis, nucleogenesis, cell proliferation and growth, cytoplasmic-nucleolar transport of ribosomal components, transcriptional repression, replication, signal transduction, inducing chromatin decondensation, etc. Nucleolin exhibits intrinsic self-cleaving, DNA helicase, RNA helicase and DNA-dependent ATPase activities. It can be phosphorylated by many protein kinases, such as the major mitotic kinase Cdc2, casein kinase 2 (CK2), and protein kinase C-zeta. Nucleolin shares similar domain architecture with gar2 from Schizosaccharomyces pombe and NSR1 from Saccharomyces cerevisiae. The highly phosphorylated N-terminal domain of nucleolin is made up of highly acidic regions separated from each other by basic sequences, and contains multiple phosphorylation sites. The central domain of nucleolin contains four closely adjacent N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), which suggests that nucleolin is potentially able to interact with multiple RNA targets. The C-terminal RGG (or GAR) domain of nucleolin is rich in glycine, arginine and phenylalanine residues, and contains high levels of NG,NG-dimethylarginines.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 755566165 340 KVLYLKNLSPRVKERDLISLFarfqeKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEF 415
Cdd:cd12405    2 KTLVVNNLSYSATEESLQSVF-----EKATSIRIPQNNGRPKGYAFVEFESVEDAKEALESCNNTEIEGRSIRLEF 72

RNA recognition motif 2 (RRM2) found in yeast multiple RNA-binding domain-containing protein 1 (MRD1) and similar proteins; This subgroup corresponds to the RRM2 of MRD1 which is encoded by a novel yeast gene MRD1 (multiple RNA-binding domain). It is well-conserved in yeast and its homologs exist in all eukaryotes. MRD1 is present in the nucleolus and the nucleoplasm. It interacts with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs (snoRNAs). It is essential for the initial processing at the A0-A2 cleavage sites in the 35 S pre-rRNA. MRD1 contains 5 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), which may play an important structural role in organizing specific rRNA processing events.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 755566165 342 LYLKNLSPRVKERDLISLFARFQEKKGPPIQFRMMTGRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVI 413
Cdd:cd12566    5 LFLRNLPYSTKEDDLQKLFSKFGEVSEVHVPIDKKTKKSKGFAYVLFLDPEDAVQAYNELDGKVFQGRLIHI 76

RNA recognition motif 3 (RRM3) found in vertebrate RNA-binding protein 47 (RBM47); This subgroup corresponds to the RRM3 of RBM47, a putative RNA-binding protein that shows high sequence homology with heterogeneous nuclear ribonucleoprotein R (hnRNP R) and heterogeneous nuclear ribonucleoprotein Q (hnRNP Q). Its biological function remains unclear. Like hnRNP R and hnRNP Q, RBM47 contains two well defined and one degenerated RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 755566165 340 KVLYLKNLSPRVKERDLISLFARFQekkgPPIQFRMMtgRMRGQAFLTFPNKDIAWQALHQINGYKLYGKILVIEFAK 417
Cdd:cd12497    2 KILYVRNLMIETTEDTIKKIFGQFN----PGCVERVK--KIRDYAFVHFASRDDAVVAMNNLNGTELEGSCIEVTLAK 73

RNA recognition motif 2 (RRM2) found in the U1A/U2B"/SNF protein family; This subfamily corresponds to the RRM2 of U1A/U2B"/SNF protein family, containing Drosophila sex determination protein SNF and its two mammalian counterparts, U1 small nuclear ribonucleoprotein A (U1 snRNP A or U1-A or U1A) and U2 small nuclear ribonucleoprotein B" (U2 snRNP B" or U2B"), all of which consist of two RNA recognition motifs (RRMs) connected by a variable, flexible linker. SNF is an RNA-binding protein found in the U1 and U2 snRNPs of Drosophila where it is essential in sex determination and possesses a novel dual RNA binding specificity. SNF binds with high affinity to both Drosophila U1 snRNA stem-loop II (SLII) and U2 snRNA stem-loop IV (SLIV). It can also bind to poly(U) RNA tracts flanking the alternatively spliced Sex-lethal (Sxl) exon, as does Drosophila Sex-lethal protein (SXL). U1A is an RNA-binding protein associated with the U1 snRNP, a small RNA-protein complex involved in pre-mRNA splicing. U1A binds with high affinity and specificity to stem-loop II (SLII) of U1 snRNA. It is predominantly a nuclear protein that shuttles between the nucleus and the cytoplasm independently of interactions with U1 snRNA. Moreover, U1A may be involved in RNA 3'-end processing, specifically cleavage, splicing and polyadenylation, through interacting with a large number of non-snRNP proteins. U2B", initially identified to bind to stem-loop IV (SLIV) at the 3' end of U2 snRNA, is a unique protein that comprises of the U2 snRNP. Additional research indicates U2B" binds to U1 snRNA stem-loop II (SLII) as well and shows no preference for SLIV or SLII on the basis of binding affinity. U2B" does not require an auxiliary protein for binding to RNA and its nuclear transport is independent on U2 snRNA binding.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 755566165 338 PNKVLYLKNLSPRVKERDLISLFARFQEKKgppiQFRMMTGrmRGQAFLTFPNKDIAWQALHQINGYKL 406
Cdd:cd12247    1 PNKILFLQNLPEETTKEMLEMLFNQFPGFK----EVRLVPR--RGIAFVEFETEEQATVALQALQGFKI 63