Hiv envelope protein gp120
external envelope protein of the human immunodeficiency virus which is encoded by the hiv env gene. It has a molecular weight of 120,000 kd and contains numerous glycosylation sites. Gp120 binds to cells expressing cd4 cell-surface antigens, most notably t4-lymphocytes and monocytes/macrophages. Gp120 has been shown to interfere with the normal function of cd4 and is at least partly responsible for the cytopathic effect of hiv.