APOBEC3G

APOBEC3G (apolipoprotein B mRNA editing enzyme, catalytic subunit 3G) is a human enzyme encoded by the ''APOBEC3G'' gene that belongs to the APOBEC superfamily of proteins. This family of proteins has been suggested to play an important role in innate anti-viral immunity. APOBEC3G belongs to the family of cytidine deaminases that catalyze the deamination of cytidine to uridine in the single stranded DNA substrate. The C-terminal domain of A3G renders catalytic activity, several NMR and crystal structures explain the substrate specificity and catalytic activity.

APOBEC3G exerts innate antiretroviral immune activity against retroviruses, most notably HIV, by interfering with proper replication. However, lentiviruses such as HIV have evolved the Viral infectivity factor (Vif) protein in order to counteract this effect. Vif interacts with APOBEC3G and triggers the ubiquitination and degradation of APOBEC3G via the proteasomal pathway. On the other hand, foamy viruses produce an accessory protein Bet () that impairs the cytoplasmic solubility of APOBEC3G. The two ways of inhibition are distinct from each other, but they can replace each other ''in vivo''. Provided by Wikipedia