gp120 envelope protein (HIV)

gp120 is a glycoprotein exposed on the surface of the HIV viral envelope and is essential for virus entry into host cells. It mediates attachment to specific cell surface receptors, primarily CD4 on helper T-cells, as well as coreceptors such as CCR5 or CXCR4. Binding to CD4 triggers conformational changes in both gp120 and its partner protein gp41, leading to fusion of the viral and cellular membranes. Gp120 is a major target for neutralizing antibodies but has evolved mechanisms—such as variable loops (V1–V5), heavy glycosylation, and conformational masking—to evade immune detection.

Other names

Envelope glycoprotein GP120SU (surface unit)

Gp120 binds to CD4 and coreceptors (CCR5 or CXCR4) to mediate HIV entry into host cells.