Human Immunodeficiency Virus Group-Specific Antigen Protein (Gag)

The group-specific antigen protein, commonly referred to as Gag, is a polyprotein encoded by the gag gene of the human immunodeficiency virus (HIV). It is a major structural protein essential for HIV virion assembly, maturation, and infectivity. Gag orchestrates multiple steps in the late phase of the viral lifecycle, including genomic RNA encapsidation, particle formation via multimerization, and interactions with both viral and host cellular proteins. It is initially synthesized as a 55 kDa precursor protein (p55), which is then cleaved by the viral protease into several mature structural proteins: Matrix (MA/p17), Capsid (CA/p24), Nucleocapsid (NC/p7), p6, and Spacer Peptides (SP1 & SP2). Failure of this cleavage results in non-infectious virions. Antibodies against Gag-derived proteins (especially p24) are widely used as diagnostic markers for early HIV infection. Disruption or inhibition of Gag processing/maturation forms the basis for some antiretroviral drug strategies.

Other names

Group-specific antigenGag polyproteinp55 precursorPr55Gag

Inhibition of Gag processing/maturation, leading to production of non-infectious virions.