Virion infectivity factor

UniProtKB accession:  P12504

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UniProtKB description:  Counteracts the innate antiviral activity of host APOBEC3F and APOBEC3G by promoting their ubiquitination and degradation. Acts as a substrate recognition component of an E3 ubiquitin-protein ligase complex: mechanistically, Vif hijacks a host cullin-5-RING E3 ubiquitin-protein ligase complex (ECS complex) and the transcription coactivator CBFB/CBF-beta to form an active E3 ubiquitin-protein ligase complex that targets APOBEC3G and APOBEC3F for polyubiquitination, leading to their degradation by the proteasome. The complex can also ubiquitinate host APOBEC3H to some extent. Vif interaction with APOBEC3G also blocks its cytidine deaminase activity in a proteasome-independent manner, suggesting a dual inhibitory mechanism. May interact directly with APOBEC3G mRNA in order to inhibit its translation. Association with CBFB/CBF-beta also inhibits the transcription coactivator activity of CBFB/CBF-beta. Seems to play a role in viral morphology by affecting the stability of the viral nucleoprotein core. Finally, Vif also contributes to the G2 cell cycle arrest observed in HIV infected cells.