Immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan, also known as HSPG2, and similar proteins. Perlecan consists of five domains: domain I has three putative heparan sulfate attachment sites, domain II has four LDL receptor-like repeats, and one Ig-like repeat, domain III resembles the short arm of laminin chains, domain IV has multiple Ig-like repeats (21 repeats in human perlecan), and domain V resembles the globular G domain of the laminin A chain and internal repeats of EGF. Perlecan may participate in a variety of biological functions including cell binding, LDL-metabolism, basement membrane assembly and selective permeability, calcium binding, and growth- and neurite-promoting activities.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1131217166 439 GQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARGMVFGIPDGVLEL 516
Cdd:cd05743     1 GETVEFTCVATGVPTPIINWRLNWGHVPDSARVSITSEGGYGTLTIRDVKESDQGAYTCEAINTRGMVFGIPDGILTV 78

SEA domain; Domain found in Sea urchin sperm protein, Enterokinase, Agrin (SEA). Proposed function of regulating or binding carbohydrate side chains. Recently a proteolytic activity has been shown for a SEA domain.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166   81 QMVYFRALVNFTHS----IDYSPQLEDAGSEEFREVSEAVVDTLESEYLKIPGDQVVSVVFIKELDGW-VFVELDVGSEG 155
Cdd:smart00200   1 PTQSFGVSLSVLSVegenLQYSPSLEDPSSEEYQELVRDVEKLLEQIYGKTDLKPDFVGTEVIEFRNGsVVVDLGLLFNE 80

                           90       100       110
                   ....*....|....*....|....*....|....*
gi 1131217166  156 NAD-GAQIQEVLHGVISSGSIASYVTSPQGFQFRR 189
Cdd:smart00200  81 GVTnGQDVEEDLLQVIKQAAYSLKITNVNVVDVLD 115

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 1131217166 343 CEPNEFPCGNGHCALKLWRCDGDFDCEDHTDEADC 377
Cdd:cd00112     1 CPPNEFRCANGRCIPSSWVCDGEDDCGDGSDEENC 35

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1131217166 217 CTEAEFACHrYNECVALEYRCDRRPDCRDMSDELDC 252
Cdd:cd00112     1 CPPNEFRCA-NGRCIPSSWVCDGEDDCGDGSDEENC 35

Immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan, also known as HSPG2, and similar proteins. Perlecan consists of five domains: domain I has three putative heparan sulfate attachment sites, domain II has four LDL receptor-like repeats, and one Ig-like repeat, domain III resembles the short arm of laminin chains, domain IV has multiple Ig-like repeats (21 repeats in human perlecan), and domain V resembles the globular G domain of the laminin A chain and internal repeats of EGF. Perlecan may participate in a variety of biological functions including cell binding, LDL-metabolism, basement membrane assembly and selective permeability, calcium binding, and growth- and neurite-promoting activities.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1131217166 439 GQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARGMVFGIPDGVLEL 516
Cdd:cd05743     1 GETVEFTCVATGVPTPIINWRLNWGHVPDSARVSITSEGGYGTLTIRDVKESDQGAYTCEAINTRGMVFGIPDGILTV 78

Laminin B (Domain IV);

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 613 FWALPEQFLGNKVDSYGGSLRYKVRYELARGTLEPVQRPDVVLVGAGHRLL--SRGHTSTQPGVPNQRQVQLSEEHWVHE 690
Cdd:pfam00052   1 YWSAPEQFLGNKLTSYGGYLTYTVRYEPLPGGGSLNSEPDVILEGNGLRLSysSPDQPPPDPGQEQTYSVRLHEENWRDS 80

Domain found in sea urchin sperm protein, enterokinase, agrin; Proposed function of regulating or binding carbohydrate sidechains.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166   81 QMVYFRALVNFTHS----IDYSPQLEDAGSEEFREVSEAVVDTLESEYLKIPGDQVVSVVFIKELDGW-VFVELDVGSEG 155
Cdd:smart00200   1 PTQSFGVSLSVLSVegenLQYSPSLEDPSSEEYQELVRDVEKLLEQIYGKTDLKPDFVGTEVIEFRNGsVVVDLGLLFNE 80

                           90       100       110
                   ....*....|....*....|....*....|....*
gi 1131217166  156 NAD-GAQIQEVLHGVISSGSIASYVTSPQGFQFRR 189
Cdd:smart00200  81 GVTnGQDVEEDLLQVIKQAAYSLKITNVNVVDVLD 115

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 1131217166 303 CGPHEAACHSGHCIPKDYVCDGQEDCADGSDEADC 337
Cdd:cd00112     1 CPPNEFRCANGRCIPSSWVCDGEDDCGDGSDEENC 35

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 1131217166 343 CEPNEFPCGNGHCALKLWRCDGDFDCEDHTDEADC 377
Cdd:cd00112     1 CPPNEFRCANGRCIPSSWVCDGEDDCGDGSDEENC 35

Low-density lipoprotein receptor domain class A; Cysteine-rich repeat in the low-density lipoprotein (LDL) receptor that plays a central role in mammalian cholesterol metabolism. The N-terminal type A repeats in LDL receptor bind the lipoproteins. Other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement. Mutations in the LDL receptor gene cause familial hypercholesterolemia.

                           10        20        30
                   ....*....|....*....|....*....|..
gi 1131217166  343 CEPNEFPCGNGHCALKLWRCDGDFDCEDHTDE 374
Cdd:smart00192   2 CPPGEFQCDNGRCIPSSWVCDGVDDCGDGSDE 33

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1131217166 386 CGPTKFRCVStNTCIPASFHCDEESDCPDRSDEFGC 421
Cdd:cd00112     1 CPPNEFRCAN-GRCIPSSWVCDGEDDCGDGSDEENC 35

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1131217166 217 CTEAEFACHrYNECVALEYRCDRRPDCRDMSDELDC 252
Cdd:cd00112     1 CPPNEFRCA-NGRCIPSSWVCDGEDDCGDGSDEENC 35

Low-density lipoprotein receptor domain class A;

                          10        20        30
                  ....*....|....*....|....*....|....*...
gi 1131217166 215 RACTEAEFACHRyNECVALEYRCDRRPDCRDMSDELDC 252
Cdd:pfam00057   1 STCSPNEFQCGS-GECIPRSWVCDGDPDCGDGSDEENC 37

Immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain of the human basement membrane heparan sulfate proteoglycan perlecan, also known as HSPG2, and similar proteins. Perlecan consists of five domains: domain I has three putative heparan sulfate attachment sites, domain II has four LDL receptor-like repeats, and one Ig-like repeat, domain III resembles the short arm of laminin chains, domain IV has multiple Ig-like repeats (21 repeats in human perlecan), and domain V resembles the globular G domain of the laminin A chain and internal repeats of EGF. Perlecan may participate in a variety of biological functions including cell binding, LDL-metabolism, basement membrane assembly and selective permeability, calcium binding, and growth- and neurite-promoting activities.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1131217166 439 GQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARGMVFGIPDGVLEL 516
Cdd:cd05743     1 GETVEFTCVATGVPTPIINWRLNWGHVPDSARVSITSEGGYGTLTIRDVKESDQGAYTCEAINTRGMVFGIPDGILTV 78

Laminin B (Domain IV);

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 613 FWALPEQFLGNKVDSYGGSLRYKVRYELARGTLEPVQRPDVVLVGAGHRLL--SRGHTSTQPGVPNQRQVQLSEEHWVHE 690
Cdd:pfam00052   1 YWSAPEQFLGNKLTSYGGYLTYTVRYEPLPGGGSLNSEPDVILEGNGLRLSysSPDQPPPDPGQEQTYSVRLHEENWRDS 80

Domain found in sea urchin sperm protein, enterokinase, agrin; Proposed function of regulating or binding carbohydrate sidechains.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166   81 QMVYFRALVNFTHS----IDYSPQLEDAGSEEFREVSEAVVDTLESEYLKIPGDQVVSVVFIKELDGW-VFVELDVGSEG 155
Cdd:smart00200   1 PTQSFGVSLSVLSVegenLQYSPSLEDPSSEEYQELVRDVEKLLEQIYGKTDLKPDFVGTEVIEFRNGsVVVDLGLLFNE 80

                           90       100       110
                   ....*....|....*....|....*....|....*
gi 1131217166  156 NAD-GAQIQEVLHGVISSGSIASYVTSPQGFQFRR 189
Cdd:smart00200  81 GVTnGQDVEEDLLQVIKQAAYSLKITNVNVVDVLD 115

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1131217166  434 IQASRGQTVTFTCVAIGVPTPIINWRLNWG-HIPSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARGMVFG 508
Cdd:smart00410   4 VTVKEGESVTLSCEASGSPPPEVTWYKQGGkLLAESGRFSVSRSGSTSTLTISNVTPEDSGTYTCAATNSSGSASS 79

Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1131217166 442 VTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARG 504
Cdd:cd00096     1 VTLTCSASGNPPPTITWYKNGKPLPPSSRDSRRSELGNGTLTISNVTLEDSGTYTCVASNSAG 63

Low-density lipoprotein receptor domain class A;

                          10        20        30
                  ....*....|....*....|....*....|....*..
gi 1131217166 301 VPCGPHEAACHSGHCIPKDYVCDGQEDCADGSDEADC 337
Cdd:pfam00057   1 STCSPNEFQCGSGECIPRSWVCDGDPDCGDGSDEENC 37

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 1131217166 343 CEPNEFPCGNGHCALKLWRCDGDFDCEDHTDEADC 377
Cdd:cd00112     1 CPPNEFRCANGRCIPSSWVCDGEDDCGDGSDEENC 35

First immunoglobulin (Ig)-like domain of neural cell adhesion molecule NCAM-2; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin (Ig)-like domain of neural cell adhesion molecule NCAM-2 (OCAM/mamFas II, RNCAM). NCAM-2 is organized similarly to NCAM-1, including five N-terminal Ig-like domains and two fibronectin type III domains. NCAM-2 is differentially expressed in the developing and mature olfactory epithelium (OE), and may function like NCAM, as an adhesion molecule. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1131217166 434 IQASRGQTVTFTCVAIGVPTPIiNWRLNWGH-IPSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARG 504
Cdd:cd05866    10 VELSVGESKFFTCTAIGEPESI-DWYNPQGEkIVSSQRVVVQKEGVRSRLTIYNANIEDAGIYRCQATDAKG 80

Fourth immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin domain of the Drosophila melanogaster Down syndrome cell adhesion molecule (DSCAM) protein and similar proteins. Down syndrome cell adhesion molecule (DSCAM) is a cell adhesion molecule that plays critical roles in neural development, including axon guidance and branching, axon target recognition, self-avoidance and synaptic formation. DSCAM belongs to the immunoglobulin superfamily and contributes to defects in the central nervous system in Down syndrome patients. Vertebrate DSCAMs differ from Drosophila Dscam1 in that they lack the extensive alternative splicing that occurs in the insect gene. Drosophila melanogaster Dscam has 38,016 isoforms generated by the alternative splicing of four variable exon clusters, which allows every neuron in the fly to display a distinctive set of Dscam proteins on its cell surface. Drosophila Dscam1 is a cell-surface protein that plays important roles in neural development and axon tiling of neurons. It is shown that thousands of isoforms bind themselves through specific homophilic (self-binding) interactions, a process which mediates cellular self-recognition. Drosophila Dscam2 is also alternatively spliced and plays a key role in the development of two visual system neurons, monopolar cells L1 and L2. This group is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1131217166 439 GQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTV---TSEGGR--GTLTIHDVKEADQGAYTCEAMNARGMV 506
Cdd:cd20956    16 GPSVSLKCVASGNPLPQITWTLDGFPIPESPRFRVgdyVTSDGDvvSYVNISSVRVEDGGEYTCTATNDVGSV 88

Third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM), and similar domains; The members here are composed of the third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM). L1 belongs to the L1 subfamily of cell adhesion molecules (CAMs) and is comprised of an extracellular region having six Ig-like domains and five fibronectin type III domains, a transmembrane region and an intracellular domain. L1 is primarily expressed in the nervous system and is involved in its development and function. L1 is associated with an X-linked recessive disorder, X-linked hydrocephalus, MASA syndrome, and spastic paraplegia type 1, that involves abnormalities of axonal growth. This group also contains the chicken neuron-glia cell adhesion molecule, Ng-CAM and human neurofascin.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1131217166 438 RGQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTvtsEGGRGTLTIHDVKEADQGAYTCEAMNARG 504
Cdd:cd05731     9 RGGVLLLECIAEGLPTPDIRWIKLGGELPKGRTKF---ENFNKTLKIENVSEADSGEYQCTASNTMG 72

Third immunoglobulin (Ig) domain of contactin-1; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig) domain of the neural cell adhesion molecule contactin-1. Contactins are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. Contactin-1 is differentially expressed in tumor tissues and may through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma. This group belongs to the I-set of IgSF domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 423 PPQVVTPPQElIQASRGQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSeggrGTLTIHDVKEADQGAYTCEAMNA 502
Cdd:cd05851     1 PADINVKFKD-TYALKGQNVTLECFALGNPVPVIRWRKILEPMPATAEISMSG----AVLKIFNIQPEDEGTYECEAENI 75

                  ...
gi 1131217166 503 RGM 505
Cdd:cd05851    76 KGK 78

Fifth immunoglobulin (Ig) domain of contactin; The members here are composed of the fifth immunoglobulin (Ig) domain of contactins. Contactins are neural cell adhesion molecules and are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. The first four Ig domains form the intermolecular binding fragment, which arranges as a compact U-shaped module via contacts between Ig domains 1 and 4, and between Ig domains 2 and 3. Contactin-2 (TAG-1, axonin-1) may play a part in the neuronal processes of neurite outgrowth, axon guidance and fasciculation, and neuronal migration. This group also includes contactin-1 and contactin-5. The different contactins show different expression patterns in the central nervous system. During development and in adulthood, contactin-2 is transiently expressed in subsets of central and peripheral neurons. Contactin-5 is expressed specifically in the rat postnatal nervous system, peaking at about 3 weeks postnatal, and a lack of contactin-5 (NB-2) results in an impairment of neuronal activity in the rat auditory system. Contactin-5 is highly expressed in the adult human brain in the occipital lobe and in the amygdala. Contactin-1 is differentially expressed in tumor tissues and may, through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1131217166 429 PPQELIQASRGQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEGgrgTLTIHDVKEADQGAYTCEAMNARG 504
Cdd:cd04969     7 PVKKKILAAKGGDVIIECKPKASPKPTISWSKGTELLTNSSRICILPDG---SLKIKNVTKSDEGKYTCFAVNFFG 79

Fourth Ig-like domain from smooth muscle myosin light chain kinase and similar domains ; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain from smooth muscle myosin light chain kinase (MYLK) and similar domains. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of this group shows that the fourth Ig-like domain from myosin light chain kinase lacks this strand and thus belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 423 PPQVVTPPQELiQASRGQTVTFTCVAIGVPTPIINWRLNWGHIpSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNA 502
Cdd:cd20976     1 APSFSSVPKDL-EAVEGQDFVAQCSARGKPVPRITWIRNAQPL-QYAADRSTCEAGVGELHIQDVLPEDHGTYTCLAKNA 78

                  ....
gi 1131217166 503 RGMV 506
Cdd:cd20976    79 AGQV 82

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1131217166 440 QTVTFTCVAIGVPTPIInWRLNWGHIPSHPRVTVtSEGGRgTLTIHDVKEADQGAYTCEAMNA 502
Cdd:cd05740    16 DAVTLTCEPETQNTSYL-WWFNGQSLPVTPRLTL-SNGNR-TLTLLNVTREDAGAYQCEISNP 75

Fourth immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; Members here are composed the fourth immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, Robo3), and three mammalian Slit homologs (Slit-1, Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, and Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 425 QVVTPPQELIQAsRGQTVTFTCVAIGVPTPIINWR------LNWGHIPSHP--RVTVTSeggRGTLTIHDVKEADQGAYT 496
Cdd:cd05726     1 QFVVKPRDQVVA-LGRTVTFQCETKGNPQPAIFWQkegsqnLLFPYQPPQPssRFSVSP---TGDLTITNVQRSDVGYYI 76

                          90
                  ....*....|
gi 1131217166 497 CEAMNARGMV 506
Cdd:cd05726    77 CQALNVAGSI 86

Seventh immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the seventh immunoglobulin domain of the Drosophila melanogaster Down syndrome cell adhesion molecule (DSCAM) protein and similar proteins. Down syndrome cell adhesion molecule (DSCAM) is a cell adhesion molecule that plays critical roles in neural development, including axon guidance and branching, axon target recognition, self-avoidance and synaptic formation. DSCAM belongs to the immunoglobulin superfamily and contributes to defects in the central nervous system in Down syndrome patients. Vertebrate DSCAMs differ from Drosophila Dscam1 in that they lack the extensive alternative splicing that occurs in the insect gene. Drosophila melanogaster Dscam has 38,016 isoforms generated by the alternative splicing of four variable exon clusters, which allows every neuron in the fly to display a distinctive set of Dscam proteins on its cell surface. Drosophila Dscam1 is a cell-surface protein that plays important roles in neural development and axon tiling of neurons. It is shown that thousands of isoforms bind themselves through specific homophilic (self-binding) interactions, a process which mediates cellular self-recognition. Drosophila Dscam2 is also alternatively spliced and plays a key role in the development of two visual system neurons, monopolar cells L1 and L2. This group is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 423 PPQVVTPPQElIQASRGQTVTFTCVAIGVPTPIINWRLNWGHIP-------SHPRVTVTSEggrGTLTIHDVKEADQGAY 495
Cdd:cd20954     1 PPRWIVEPVD-ANVAAGQDVMLHCQADGFPTPTVTWKKATGSTPgeykdllYDPNVRILPN---GTLVFGHVQKENEGHY 76

                  ....*....
gi 1131217166 496 TCEAMNARG 504
Cdd:cd20954    77 LCEAKNGIG 85

Third immunoglobulin (Ig)-like domain of peroxidasin; The members here are composed of the third immunoglobulin (Ig)-like domain in peroxidasin. Peroxidasin has a peroxidase domain and interacting extracellular motifs containing four Ig-like domains. It has been suggested that peroxidasin is secreted and has functions related to the stabilization of the extracellular matrix. It may play a part in various other important processes such as removal and destruction of cells which have undergone programmed cell death and protection of the organism against non-self.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1131217166 439 GQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEggrGTLTIHDVKEADQGAYTCEAMNARGMV 506
Cdd:cd05745     2 GQTVDFLCEAQGYPQPVIAWTKGGSQLSVDRRHLVLSS---GTLRISRVALHDQGQYECQAVNIVGSQ 66

Immunoglobulin (Ig)-like domain of myotilin, palladin, and myopalladin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in myotilin, palladin, and myopalladin. Myotilin, palladin, and myopalladin function as scaffolds that regulate actin organization. Myotilin and myopalladin are most abundant in skeletal and cardiac muscle; palladin is ubiquitously expressed in the organs of developing vertebrates and plays a key role in cellular morphogenesis. The three family members each interact with specific molecular partners with all three binding to alpha-actinin; In addition, palladin also binds to vasodilator-stimulated phosphoprotein (VASP) and ezrin, myotilin binds to filamin and actin, and myopalladin also binds to nebulin and cardiac ankyrin repeat protein (CARP). This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 424 PQVVTPPQELiQASRGQTVTFTCVAIGVPTPIINWRLNwGHI--PSHPRVTVTSEGGRGTLTIHDVKEADQGAYTCEAMN 501
Cdd:cd05744     1 PHFLQAPGDL-EVQEGRLCRFDCKVSGLPTPDLFWQLN-GKPvrPDSAHKMLVRENGRHSLIIEPVTKRDAGIYTCIARN 78

                  ....*
gi 1131217166 502 ARGMV 506
Cdd:cd05744    79 RAGEN 83

Low Density Lipoprotein Receptor Class A domain, a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism; the receptor protein binds LDL and transports it into cells by endocytosis; 7 successive cysteine-rich repeats of about 40 amino acids are present in the N-terminal of this multidomain membrane protein; other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement; the binding of calcium is required for in vitro formation of the native disulfide isomer and is necessary in establishing and maintaining the modular structure

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                  ....*....|....*....|....*....|....*.
gi 1131217166 217 CTEAEFACHrYNECVALEYRCDRRPDCRDMSDELDC 252
Cdd:cd00112     1 CPPNEFRCA-NGRCIPSSWVCDGEDDCGDGSDEENC 35

Low-density lipoprotein receptor domain class A; Cysteine-rich repeat in the low-density lipoprotein (LDL) receptor that plays a central role in mammalian cholesterol metabolism. The N-terminal type A repeats in LDL receptor bind the lipoproteins. Other homologous domains occur in related receptors, including the very low-density lipoprotein receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor, and in proteins which are functionally unrelated, such as the C9 component of complement. Mutations in the LDL receptor gene cause familial hypercholesterolemia.

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                   ....*....|....*....|....*....|...
gi 1131217166  386 CGPTKFRCvSTNTCIPASFHCDEESDCPDRSDE 418
Cdd:smart00192   2 CPPGEFQC-DNGRCIPSSWVCDGVDDCGDGSDE 33

Third immunoglobulin-like domain of the human WFIKKN (WAP, follistatin, immunoglobulin, Kunitz and NTR domain-containing protein), and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin-like domain of the human WFIKKN (WAP, follistatin, immunoglobulin, Kunitz and NTR domain-containing protein) and similar proteins. WFIKKN is a secreted protein that consists of multiple types of protease inhibitory modules, including two tandem Kunitz-type protease inhibitor-domains. The Ig superfamily is a heterogenous group of proteins built on a common fold comprised of a sandwich of two beta sheets. Members of the Ig superfamily are components of immunoglobulin, neuroglia, cell surface glycoproteins, such as T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, such as butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 423 PPQVVTPPQELIQAsrGQTVTFTCVAIGVPTPIINW------RLNWGHIPSHPR--VTVTSeggRGTLTIHDVKEADQGA 494
Cdd:cd05765     1 PALVNSPTHQTVKV--GETASFHCDVTGRPQPEITWekqvpgKENLIMRPNHVRgnVVVTN---IGQLVIYNAQPQDAGL 75

                          90
                  ....*....|..
gi 1131217166 495 YTCEAMNARGMV 506
Cdd:cd05765    76 YTCTARNSGGLL 87

C-terminal immunoglobulin (Ig)-like domain of myotilin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the C-terminal immunoglobulin (Ig)-like domain of myotilin. Mytolin belongs to the palladin-myotilin-myopalladin family. Proteins belonging to the latter family contain multiple Ig-like domains and function as scaffolds, modulating the actin cytoskeleton. Myotilin is most abundant in skeletal and cardiac muscle and is involved in maintaining sarcomere integrity. It binds to alpha-actinin, filamin, and actin. Mutations in myotilin lead to muscle disorders. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1131217166 424 PQVVTPPQElIQASRGQTVTFTCVAIGVPTPIINWRLNWGHIPSHP-RVTVTSEG-GRGTLTIHDVKEADQGAYTCEAMN 501
Cdd:cd05892     1 PMFIQKPQN-KKVLEGDPVRLECQISAIPPPQIFWKKNNEMLQYNTdRISLYQDNcGRICLLIQNANKKDAGWYTVSAVN 79

                  ....*
gi 1131217166 502 ARGMV 506
Cdd:cd05892    80 EAGVV 84

Immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins; member of the I-set of IgSF domains; This group contains the immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins. The SALM (for synaptic adhesion-like molecules; also known as Lrfn for leucine-rich repeat and fibronectin type III domain containing) family of adhesion molecules consists of five known members: SALM1/Lrfn2, SALM2/Lrfn1, SALM3/Lrfn4, SALM4/Lrfn3, and SALM5/Lrfn5. SALMs share a similar domain structure, containing leucine-rich repeats (LRRs), an immunoglobulin (Ig) domain, and a fibronectin III (FNIII) domain, followed by a transmembrane domain and a C-terminal PDZ-binding motif. SALM5 is implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons. SALM5 interacts with the Ig domains of LAR (Leukocyte common Antigen-Related) family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPdelta, and PTPsigma). In addition, PTPdelta is implicated in ASDs, ADHD, bipolar disorder, and restless leg syndrome. Studies have shown that LAR-RPTPs are novel and splicing-dependent presynaptic ligands for SALM5, and that they mediate SALM5-dependent presynaptic differentiation. Furthermore, SALM5 maintains AMPA receptor (AMPAR)-mediated excitatory synaptic transmission through mechanisms involving the interaction of SALM5 with LAR-RPTPs. This group belongs to the I-set of immunoglobulin superfamily (IgSF) domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1131217166 439 GQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEGGRGTLTIHDVKeaDQGAYTCEAMNARG 504
Cdd:cd05764    15 GQRATLRCKARGDPEPAIHWISPEGKLISNSSRTLVYDNGTLDILITTVK--DTGAFTCIASNPAG 78

immunoglobulin-like domain of telokin and similar proteins; a member of the I-set of IgSF domains; The members here are composed of the immunoglobulin (Ig) domain in telokin, the C-terminal domain of myosin light chain kinase which is identical to telokin, and similar proteins. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the telokin Ig domain lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1131217166 437 SRGQTVTFTCVAIGVPTPIINWRLNWGHIPSHPRVTVTSEG-GRGTLTIHDVKEADQGAYTCEAMNARG 504
Cdd:cd20973    10 VEGSAARFDCKVEGYPDPEVKWMKDDNPIVESRRFQIDQDEdGLCSLIISDVCGDDSGKYTCKAVNSLG 78

Immunoglobulin (Ig)-like I-set domain of Neural Cell Adhesion Molecule 1 (NCAM-1); The members here are composed of the fourth Ig domain of Neural Cell Adhesion Molecule 1(NCAM-1). NCAM plays important roles in the development and regeneration of the central nervous system, in synaptogenesis and neural migration. NCAM mediates cell-cell and cell-substratum recognition and adhesion via homophilic (NCAM-NCAM) and heterophilic (NCAM-non-NCAM) interactions. NCAM is expressed as three major isoforms having different intracellular extensions. The extracellular portion of NCAM has five N-terminal Ig-like domains and two fibronectin type III domains. The double zipper adhesion complex model for NCAM homophilic binding involves Ig1, Ig2, and Ig3. By this model, Ig1 and Ig2 mediate dimerization of NCAM molecules situated on the same cell surface (cis interactions), and Ig3 domains mediate interactions between NCAM molecules expressed on the surface of opposing cells (trans interactions), through binding to the Ig1 and Ig2 domains. The adhesive ability of NCAM is modulated by the addition of polysialic acid chains to the fifth Ig-like domain. One of the unique features of I-set domains is the lack of a C" strand. The structures of this group show that the Ig domain lacks this strand and thus is a member of the I-set of Ig domains.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1131217166 442 VTFTCVAIGVPTPIINWRLNWGHIPSHP-----RVTVTSEGGRGTLTIHDVKEADQGAYTCEAMNARG 504
Cdd:cd05869    20 ITLTCEASGDPIPSITWRTSTRNISSEEktldgHIVVRSHARVSSLTLKYIQYTDAGEYLCTASNTIG 87