Plays a role in viral particle release. Presumably acts by facilitating the fission of the virion bud at the cell surface (PubMed:17267509, PubMed:22828015). May prevent the antiviral activity of murine APOBEC3 (PubMed:25505062, PubMed:23671100, PubMed:20702647). Glycosylated by host (PubMed:6997511). Cleaved by host near the middle of the molecule, releasing the c-terminal half containing capsid and nucleoprotein domains op GAG (PubMed:9188605). The protein uses an unusual AUG start codon with leucine.