Biosynthesis, cleavage, and degradation of the human immunodeficiency virus 1 envelope glycoprotein gp160

Abstract

The synthesis and processing of the human immunodeficiency virus 1 (HIV-1) envelope precursor glycoprotein gp 160 was studied in an infected CD4+ lymphocytic cell line. Surprisingly, only a small percentage (5-15%) of gp160 is cleaved to produce the mature gp120 component. Intracellular sorting results in the transfer of most uncleaved gp160 to lysosomes, where it is degraded, while gp120 is transported to the cell surface and subsequently secreted. Cleavage of gp160 to generate gp120 occurs intracellularly and can be inhibited by NH4Cl. Taken together, these results indicate that intracellular cleavage of gp160 determines the intracellular transport and survival of the envelope glycoproteins necessary to produce infectious virus.