Figure 4

Eight sub-groups of the betaretrovirus genus. A schematic diagram for a single representative of each group is depicted. Core retroviral genes gag, pro, pol, and env are bordered by the proviral long terminal repeats (LTRs). Also shown are other major genetic features such as open reading frames (ORFs) greater than 300nt in length and the rec gene of HERV-K113, enzymatic active site motifs of protease (D×G), reverse transcriptase (DDD), and integrase (DDE); the primer binding site (PBS) and polypurine tracts (PPT); and the characteristic betaretroviral dUTPase domain. NSR: non-sequenced region. ORF* is part of foreign nucleotide insertion within MlERV-βA and does not appear to be a retroviral element.