Envelope glycoprotein gp41 (None)

Envelope glycoprotein gp41 is a transmembrane protein that forms part of the envelope glycoprotein complex (Env) of human immunodeficiency virus type 1 (HIV-1). It is non-covalently associated with the surface subunit gp120. While gp120 mediates viral attachment to host cell receptors, gp41 is responsible for catalyzing the fusion between viral and cellular membranes, a critical step in HIV entry into target cells. The core structure of activated/fusion-active gp41 is a six-helical bundle: three HR1 helices form an interior coiled-coil trimer, while three HR2 helices pack antiparallel into hydrophobic grooves on this trimer. This conformation brings viral and cellular membranes close together to facilitate fusion. Mutations within conserved residues such as Q563 in HR1 can significantly affect fusogenic activity and infectivity.

Inhibition of gp41-mediated membrane fusion