Gag polyprotein, HIV2 (Gag)

The Gag polyproteins of human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) have 50% sequence homology, and each contains N-terminal matrix (MA) domain responsible for Gag targeting and binding to the plasma membrane, capsid domain (CA) that promote Gag multimerization, and nucleocapsid (NC) domain that interacts with viral and cellular nucleic acids. Gag also contains two spacer regions (SP1, SP2) and the p6 domain located at the C-terminal, which is necessary for the virus release from infected cells. Gag polyprotein is cleaved into freestanding MA, CA, and NC proteins by viral proteases in a highly ordered manner before or shortly after the release of the virion. Gag polyprotein is a multifunctional regulator of retroviral replication and the main structural component of immature virions. The expression of HIV-1 or HIV-2 Gag alone can result in the production of virus-like particles that bud out of cells.