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.

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gi 407227464   1 MTKILEPFRTKNPEIVIYQYMDDLYVGSDLEiGQHRAKIEELREHLLKWGFTTPDKKHQ 59
Cdd:cd01645  144 VAQALEPFRKQYPDIVIYHYMDDILIASDLE-GQLREIYEELRQTLLRWGLTIPPEKVQ 201

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.

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gi 407227464   1 MTKILEPFRTKNPEIVIYQYMDDLYVGSDLEiGQHRAKIEELREHLLKWGFTTPDKKHQ 59
Cdd:cd01645  144 VAQALEPFRKQYPDIVIYHYMDDILIASDLE-GQLREIYEELRQTLLRWGLTIPPEKVQ 201

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.

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                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 407227464   1 MTKILEPFRTKNPEIVIYQYMDDLYVGSDLEiGQHRAKIEELREHLLKWGFTTPDKKHQ 59
Cdd:cd01645  144 VAQALEPFRKQYPDIVIYHYMDDILIASDLE-GQLREIYEELRQTLLRWGLTIPPEKVQ 201

Reverse transcriptase (RNA-dependent DNA polymerase); A reverse transcriptase gene is usually indicative of a mobile element such as a retrotransposon or retrovirus. Reverse transcriptases occur in a variety of mobile elements, including retrotransposons, retroviruses, group II introns, bacterial msDNAs, hepadnaviruses, and caulimoviruses.

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gi 407227464    1 MTKILEPFRTKnPEIVIYQYMDDLYVGSDlEIGQHRAKIEELREHLLKWGFTTPDKKHQ 59
Cdd:pfam00078 118 MNELLRPLRKR-AGLTLVRYADDILIFSK-SEEEHQEALEEVLEWLKESGLKINPEKTQ 174