Immunological analysis of human immunodeficiency virus type 1 envelope glycoprotein proteolytic cleavage.

Two potential cleavage sites have been identified on precursor gp 160 of human immunodeficiency virus type 1. Using antibodies directed against the C-terminus of gp 120, including the sequence between the two sites, we have shown that nonmutated viral and recombinant gp 160 are cleaved at both sites: the great majority of molecules are cleaved at site 1 (Arg-Glu-Lys-Arg), and gp41 can then associate as an oligomer; a minority of molecules are cleaved at site 2 (Lys-Ala-Lys-Arg-Arg) and the corresponding gp41 appears to present as a monomer. This could reflect two different processing pathways for gp41 biosynthesis, one of which only may result in biologically active molecules according to the literature.