Gag precursors of HIV and SIV are cleaved into six proteins found in the mature virions

During retroviral maturation gag precursors are proteolytically cleaved to mature gag proteins. The number of mature gag proteins and their order in the gag precursors of HIV-I3B, SIVMne (captive macaque isolate), and SIVCat (wild mangabey isolate) has been determined by N-terminal amino acid sequence analysis of mature gag proteins and alignment with predicted sequences of homologous gag precursors. For HIV-1 and SIVs maturation proteolysis results in six gag proteins and the gag precursor cleavage pattern is distinctive and different from cleavage patterns for all other known retroviruses.