Envelope glycoprotein gp120 (C5 domain) (gp120 (C5 domain))

Envelope glycoprotein gp120 is a surface-exposed component of the HIV envelope spike complex that plays a critical role in virus attachment and entry into host cells. The protein is initially synthesized as part of a larger precursor, gp160, which is cleaved by host proteases such as furin at specific sites including within the C5 domain; this cleavage produces mature gp120 and its transmembrane partner, gp41[3][4][5]. The C5 domain encompasses part of this cleavage site and contributes structurally to proper folding and maturation. Gp120 binds first to CD4 on target T-cells or other susceptible cells, triggering conformational changes that allow subsequent interaction with chemokine co-receptors CCR5 or CXCR4. These events ultimately lead to exposure of fusion elements in gp41 required for membrane fusion between virus and cell[1][2]. The structure includes inner and outer domains stabilized by disulfide bonds; these are essential for correct folding—especially within β-barrel regions—and thus for infectivity[6]. Gp120’s high variability enables immune escape but also presents conserved regions such as parts of V3 loop or structural motifs that are targets for broadly neutralizing antibodies. While not itself an enzyme or classical human receptor/ion channel/transporter, it is considered a key therapeutic target due to its central role in HIV infection biology. The "C5" designation refers specifically to one subdomain near the carboxy terminus involved in maturation processing; while not typically targeted directly by drugs or vaccines at present, understanding its structure has informed strategies against Env-mediated viral entry[3][4]. No evidence suggests this target name is misspelled or otherwise incorrect based on current literature.

Other names

HIV-1 envelope glycoprotein gp120 C5 domainHIV Env gp120 C5GP120 C5 region

Inhibition of receptor binding to CD4 and/or chemokine co-receptors prevents viral entry[2]