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. 2020 Oct 27;12(11):1217. doi: 10.3390/v12111217

Figure 2.

Figure 2

Mouse mammary tumor virus (MMTV) and murine leukemia virus (MLV) proteins that counteract APOBEC3. (A) Diagram of MLV genome and identified viral anti-APOBEC3 proteins. GlycoGag translation initiation from a CUG upstream from the Gag translation start site. Red lines indicate glycosylation sites. P50 is generated from an alternatively spliced mRNA that results in a protein encoding matrix (MA), p12, the N terminus of capsid (CA) and the C terminus of integrase (IN). The MLV PR has also been shown to degrade APOBEC3. Finally, it has been suggested that MMTV RT prevents APOBEC3 deamination activity by its rapid processivity. (B) The role of glycoGag and P50 in blocking APOBEC3. GlycoGag (red branched lines) prevents APOBEC3 from accessing the reverse transcription complex, and P50 prevents packaging of APOBEC3; both of proteins thereby facilitate reverse transcription in newly infected cells. Reverse transcription is inhibited by APOBEC3 after infection with virions lacking glycoGag, loss of which destabilizes the capsid, or lacking P50.