conserved catalytic core domain of RNA-dependent RNA polymerase (RdRp) from the positive-sense single-stranded RNA [(+)ssRNA] viruses and closely related viruses; This family contains the catalytic core domain of RdRp of RNA viruses which belong to Group IV of the Baltimore classification system, and are a group of related viruses that have positive-sense (+), single-stranded (ss) genomes made of ribonucleic acid (RNA). RdRp (also known as RNA replicase) catalyzes the replication of RNA from an RNA template; specifically, it catalyzes the synthesis of the RNA strand complementary to a given RNA template. The Baltimore Classification is divided into 7 classes, 3 of which include RNA viruses: Group IV (+) RNA viruses, Group III double-stranded (ds) RNA viruses, and Group V negative-sense (-) RNA viruses. Baltimore groups of viruses differ with respect to the nature of their genome (i.e., the nucleic acid form that is packaged into virions) and correspond to distinct strategies of genome replication and expression. (+) viral RNA is similar to mRNA and thus can be immediately translated by the host cell. (+)ssRNA viruses can also produce (+) copies of the genome from (-) strands of an intermediate dsRNA genome. This acts as both a transcription and a replication process since the replicated RNA is also mRNA. RdRps belong to the expansive class of polymerases containing so-called palm catalytic domains along with the accessory fingers and thumb domains. All RdRps also have six conserved structural motifs (A-F), located in its majority in the palm subdomain (A-E motifs) and the F motif is located on the finger subdomain. All these motifs have been shown to be implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides. In addition to Group IV viruses, this model also includes Picobirnaviruses (PBVs), members of the family Picobirnaviridae of dsRNA viruses (Baltimore classification Group III), which are bi-segmented dsRNA viruses. The phylogenetic tree of the RdRps of RNA viruses (realm Riboviria) showed that picobirnaviruses are embedded in the branch of diverse (+)RNA viruses; sometimes they are collectively referred to as the picornavirus supergroup. RdRps of members of the family Permutatetraviridae, a distinct group of RNA viruses that encompass a circular permutation within the RdRp palm domain, are not included in this model.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 118 GPKVKQWPLTEEKIKALVEICTEMEKEGKISKIGpeNPYNTPVFAIKKKDStKWRKVVDFRELNKRTQDFWEVQLGIPHP 197
Cdd:cd01645     1 PVWIKQWPLTEEKLEALTELVTEQLKEGHIEPST--SPWNTPVFVIKKKSG-KWRLLHDLRAVNAQTQDMGALQPGLPHP 77

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 198 AGIGKNKSVTVLDVGDAYFSVPLDESFRKYTAFTIPSINNETPGIRYQYNVLPQGWKGSPAIFQSSMTKILEPFRLKNPE 277
Cdd:cd01645    78 AALPKGWPLIVLDLKDCFFSIPLHPDDRERFAFTVPSINNKGPAKRYQWKVLPQGMKNSPTICQSFVAQALEPFRKQYPD 157

                         170       180       190       200       210
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 2770806377 278 MIIYQYMDDLYVGSDLEiGQHRIKIEELRAHLLSWGFTTPDKKHQKEPPFLWMGYEL 334
Cdd:cd01645   158 IVIYHYMDDILIASDLE-GQLREIYEELRQTLLRWGLTIPPEKVQKEPPFQYLGYEL 213

Retroviral aspartyl protease; Single domain aspartyl proteases from retroviruses, retrotransposons, and badnaviruses (plant dsDNA viruses). These proteases are generally part of a larger polyprotein; usually pol, more rarely gag. Retroviral proteases appear to be homologous to a single domain of the two-domain eukaryotic aspartyl proteases such as pepsins, cathepsins, and renins (pfam00026).

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377   6 LWQRPLVTIKIEGQLKEALLDTGADDTVLEDINLPGKW----KPRMIGGIGGFIKVRQYEQICIEICGKKAIGTV--LVG 79
Cdd:pfam00077   1 AEQRPLLTVKIGGKYFTALLDTGADDTVISQNDWPTNWpkqkATTNIQGIGGGINVRQSDQILILIGEDKFRGTVspLIL 80

                          90       100
                  ....*....|....*....|.
gi 2770806377  80 PT-PVNIIGRNMLTQLGCTLN 99
Cdd:pfam00077  81 PTcPVNIIGRDLLQQLGGRLT 101

RT_Rtv: Reverse transcriptases (RTs) from retroviruses (Rtvs). RTs catalyze the conversion of single-stranded RNA into double-stranded viral DNA for integration into host chromosomes. Proteins in this subfamily contain long terminal repeats (LTRs) and are multifunctional enzymes with RNA-directed DNA polymerase, DNA directed DNA polymerase, and ribonuclease hybrid (RNase H) activities. The viral RNA genome enters the cytoplasm as part of a nucleoprotein complex, and the process of reverse transcription generates in the cytoplasm forming a linear DNA duplex via an intricate series of steps. This duplex DNA is colinear with its RNA template, but contains terminal duplications known as LTRs that are not present in viral RNA. It has been proposed that two specialized template switches, known as strand-transfer reactions or "jumps", are required to generate the LTRs.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 118 GPKVKQWPLTEEKIKALVEICTEMEKEGKISKIGpeNPYNTPVFAIKKKDStKWRKVVDFRELNKRTQDFWEVQLGIPHP 197
Cdd:cd01645     1 PVWIKQWPLTEEKLEALTELVTEQLKEGHIEPST--SPWNTPVFVIKKKSG-KWRLLHDLRAVNAQTQDMGALQPGLPHP 77

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 198 AGIGKNKSVTVLDVGDAYFSVPLDESFRKYTAFTIPSINNETPGIRYQYNVLPQGWKGSPAIFQSSMTKILEPFRLKNPE 277
Cdd:cd01645    78 AALPKGWPLIVLDLKDCFFSIPLHPDDRERFAFTVPSINNKGPAKRYQWKVLPQGMKNSPTICQSFVAQALEPFRKQYPD 157

                         170       180       190       200       210
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 2770806377 278 MIIYQYMDDLYVGSDLEiGQHRIKIEELRAHLLSWGFTTPDKKHQKEPPFLWMGYEL 334
Cdd:cd01645   158 IVIYHYMDDILIASDLE-GQLREIYEELRQTLLRWGLTIPPEKVQKEPPFQYLGYEL 213

Reverse transcriptase connection domain; This domain is known as the connection domain. This domain lies between the thumb and palm domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 418 YYEPSKDLIAEVQKQGQDQWTYQIYQEPFKNLKTGKYARQGSAHTNDVKQLTAVVQKIATESIVIWGKTPKFRLPIQKET 497
Cdd:pfam06815   1 YYDPSKDLIAEIQKQGQGQWTYQIYQEPFKNLKTGKYARMRGAHTNDVKQLTEAVQKITTESIVIWGKTPKFKLPIQKET 80

                          90       100
                  ....*....|....*....|..
gi 2770806377 498 WETWWTEYWQATWIPEWEFVNT 519
Cdd:pfam06815  81 WETWWTEYWQATWIPEWEFVNT 102

Retropepsins, pepsin-like aspartate proteases; This is a subfamily of retropepsins. The family includes pepsin-like aspartate proteases from retroviruses, retrotransposons and retroelements. While fungal and mammalian pepsins are bilobal proteins with structurally related N- and C-termini, retropepsins are half as long as their fungal and mammalian counterparts. The monomers are structurally related to one lobe of the pepsin molecule and retropepsins function as homodimers. The active site aspartate occurs within a motif (Asp-Thr/Ser-Gly), as it does in pepsin. Retroviral aspartyl protease is synthesized as part of the POL polyprotein that contains an aspartyl protease, a reverse transcriptase, RNase H, and an integrase. The POL polyprotein undergoes specific enzymatic cleavage to yield the mature proteins. In aspartate peptidases, Asp residues are ligands of an activated water molecule in all examples where catalytic residues have been identified. This group of aspartate peptidases is classified by MEROPS as the peptidase family A2 (retropepsin family, clan AA), subfamily A2A.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377  12 VTIKIEGQLKEALLDTGADDTVLEDINLPGKW----KPRMIGGIGGFIKVRQYEQICIEICGKKAIGTVLVGP--TPVNI 85
Cdd:cd05482     1 LTLYINGKLFEGLLDTGADVSIIAENDWPKNWpiqpAPSNLTGIGGAITPSQSSVLLLEIDGEGHLGTILVYVlsLPVNL 80

                  ....*..
gi 2770806377  86 IGRNMLT 92
Cdd:cd05482    81 WGRDILS 87

RT_Rtv: Reverse transcriptases (RTs) from retroviruses (Rtvs). RTs catalyze the conversion of single-stranded RNA into double-stranded viral DNA for integration into host chromosomes. Proteins in this subfamily contain long terminal repeats (LTRs) and are multifunctional enzymes with RNA-directed DNA polymerase, DNA directed DNA polymerase, and ribonuclease hybrid (RNase H) activities. The viral RNA genome enters the cytoplasm as part of a nucleoprotein complex, and the process of reverse transcription generates in the cytoplasm forming a linear DNA duplex via an intricate series of steps. This duplex DNA is colinear with its RNA template, but contains terminal duplications known as LTRs that are not present in viral RNA. It has been proposed that two specialized template switches, known as strand-transfer reactions or "jumps", are required to generate the LTRs.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 118 GPKVKQWPLTEEKIKALVEICTEMEKEGKISKIGpeNPYNTPVFAIKKKDStKWRKVVDFRELNKRTQDFWEVQLGIPHP 197
Cdd:cd01645     1 PVWIKQWPLTEEKLEALTELVTEQLKEGHIEPST--SPWNTPVFVIKKKSG-KWRLLHDLRAVNAQTQDMGALQPGLPHP 77

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 198 AGIGKNKSVTVLDVGDAYFSVPLDESFRKYTAFTIPSINNETPGIRYQYNVLPQGWKGSPAIFQSSMTKILEPFRLKNPE 277
Cdd:cd01645    78 AALPKGWPLIVLDLKDCFFSIPLHPDDRERFAFTVPSINNKGPAKRYQWKVLPQGMKNSPTICQSFVAQALEPFRKQYPD 157

                         170       180       190       200       210
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 2770806377 278 MIIYQYMDDLYVGSDLEiGQHRIKIEELRAHLLSWGFTTPDKKHQKEPPFLWMGYEL 334
Cdd:cd01645   158 IVIYHYMDDILIASDLE-GQLREIYEELRQTLLRWGLTIPPEKVQKEPPFQYLGYEL 213

Reverse transcriptase connection domain; This domain is known as the connection domain. This domain lies between the thumb and palm domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 418 YYEPSKDLIAEVQKQGQDQWTYQIYQEPFKNLKTGKYARQGSAHTNDVKQLTAVVQKIATESIVIWGKTPKFRLPIQKET 497
Cdd:pfam06815   1 YYDPSKDLIAEIQKQGQGQWTYQIYQEPFKNLKTGKYARMRGAHTNDVKQLTEAVQKITTESIVIWGKTPKFKLPIQKET 80

                          90       100
                  ....*....|....*....|..
gi 2770806377 498 WETWWTEYWQATWIPEWEFVNT 519
Cdd:pfam06815  81 WETWWTEYWQATWIPEWEFVNT 102

RT_ZFREV_like: A subfamily of reverse transcriptases (RTs) found in sequences similar to the intact endogenous retrovirus ZFERV from zebrafish and to Moloney murine leukemia virus RT. An RT gene is usually indicative of a mobile element such as a retrotransposon or retrovirus. RTs occur in a variety of mobile elements, including retrotransposons, retroviruses, group II introns, bacterial msDNAs, hepadnaviruses, and caulimoviruses. These elements can be divided into two major groups. One group contains retroviruses and DNA viruses whose propagation involves an RNA intermediate. They are grouped together with transposable elements containing long terminal repeats (LTRs). The other group, also called poly(A)-type retrotransposons, contain fungal mitochondrial introns and transposable elements that lack LTRs. Phylogenetic analysis suggests that ZFERV belongs to a distinct group of retroviruses.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 119 PKVKQWPLTEEKIKALVEICTEMEKEGKIskIGPENPYNTPVFAIKKKDSTKWRKVVDFRELNKRTQDfweVQLGIPHPA 198
Cdd:cd03715     2 VNQKQYPLPREAREGITPHIQELLEAGIL--VPCQSPWNTPILPVKKPGGNDYRMVQDLRLVNQAVLP---IHPAVPNPY 76

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 199 GI-----GKNKSVTVLDVGDAYFSVPLDESFRKYTAFTIPsinnetpGIRYQYNVLPQGWKGSPAIFQSSMTKILEPFRL 273
Cdd:cd03715    77 TLlsllpPKHQWYTVLDLANAFFSLPLAPDSQPLFAFEWE-------GQQYTFTRLPQGFKNSPTLFHEALARDLAPFPL 149

                         170       180       190       200
                  ....*....|....*....|....*....|....*....|....*....
gi 2770806377 274 KNPEMIIYQYMDDLYVGSDLEiGQHRIKIEELRAHLLSWGFTTPDKKHQ 322
Cdd:cd03715   150 EHEGTILLQYVDDLLLAADSE-EDCLKGTDALLTHLGELGYKVSPKKAQ 197

Retropepsins, pepsin-like aspartate proteases; This is a subfamily of retropepsins. The family includes pepsin-like aspartate proteases from retroviruses, retrotransposons and retroelements. While fungal and mammalian pepsins are bilobal proteins with structurally related N- and C-termini, retropepsins are half as long as their fungal and mammalian counterparts. The monomers are structurally related to one lobe of the pepsin molecule and retropepsins function as homodimers. The active site aspartate occurs within a motif (Asp-Thr/Ser-Gly), as it does in pepsin. Retroviral aspartyl protease is synthesized as part of the POL polyprotein that contains an aspartyl protease, a reverse transcriptase, RNase H, and an integrase. The POL polyprotein undergoes specific enzymatic cleavage to yield the mature proteins. In aspartate peptidases, Asp residues are ligands of an activated water molecule in all examples where catalytic residues have been identified. This group of aspartate peptidases is classified by MEROPS as the peptidase family A2 (retropepsin family, clan AA), subfamily A2A.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377  12 VTIKIEGQLKEALLDTGADDTVLEDINLPGKW----KPRMIGGIGGFIKVRQYEQICIEICGKKAIGTVLVGP--TPVNI 85
Cdd:cd05482     1 LTLYINGKLFEGLLDTGADVSIIAENDWPKNWpiqpAPSNLTGIGGAITPSQSSVLLLEIDGEGHLGTILVYVlsLPVNL 80

                  ....*..
gi 2770806377  86 IGRNMLT 92
Cdd:cd05482    81 WGRDILS 87

RT_like: Reverse transcriptase (RT, RNA-dependent DNA polymerase)_like family. An RT gene is usually indicative of a mobile element such as a retrotransposon or retrovirus. RTs occur in a variety of mobile elements, including retrotransposons, retroviruses, group II introns, bacterial msDNAs, hepadnaviruses, and caulimoviruses. These elements can be divided into two major groups. One group contains retroviruses and DNA viruses whose propagation involves an RNA intermediate. They are grouped together with transposable elements containing long terminal repeats (LTRs). The other group, also called poly(A)-type retrotransposons, contain fungal mitochondrial introns and transposable elements that lack LTRs.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377 249 LPQGWKGSPAIFQSSMTKILEPFRLKNPEMIIYQYMDDLYVGSDLEigQHRIKIEELRAHLLSWGFTTPDKKHQ---KEP 325
Cdd:cd00304    12 LPQGSPLSPALANLYMEKLEAPILKQLLDITLIRYVDDLVVIAKSE--QQAVKKRELEEFLARLGLNLSDEKTQfteKEK 89

                  ....*....
gi 2770806377 326 PFLWMGYEL 334
Cdd:cd00304    90 KFKFLGILV 98

Retropepsin of the RTVL_H family of human endogenous retrovirus-like elements; This family includes aspartate proteases from retroelements with LTR (long terminal repeats) including the RTVL_H family of human endogenous retrovirus-like elements. While fungal and mammalian pepsins are bilobal proteins with structurally related N- and C-termini, retropepsins are half as long as their fungal and mammalian counterparts. The monomers are structurally related to one lobe of the pepsin molecule and retropepsins function as homodimers. The active site aspartate occurs within a motif (Asp-Thr/Ser-Gly), as it does in pepsin. Retroviral aspartyl protease is synthesized as part of the POL polyprotein that contains an aspartyl protease, a reverse transcriptase, RNase H, and an integrase. The POL polyprotein undergoes specific enzymatic cleavage to yield the mature proteins. In aspartate peptidases, Asp residues are ligands of an activated water molecule in all examples where catalytic residues have been identified. This group of aspartate peptidases is classified by MEROPS as the peptidase family A2 (retropepsin family, clan AA), subfamily A2A.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2770806377  12 VTIKIEGQLKEALLDTGADDTVL-EDINLPGKWKPR--MIGGIGGFIK--VRQYEQICiEICGKKAIGTVLVGPT-PVNI 85
Cdd:cd06095     1 VTITVEGVPIVFLVDTGATHSVLkSDLGPKQELSTTsvLIRGVSGQSQqpVTTYRTLV-DLGGHTVSHSFLVVPNcPDPL 79

                  ....*..
gi 2770806377  86 IGRNMLT 92
Cdd:cd06095    80 LGRDLLS 86