[The Molecular Clamp is a trimerization motif of 80aa in length (~9.2 kDa) derived from N- and C-terminal heptad repeat (HR) regions of HIV-1 gp41 which self-assemble into a stable six-helical bundle structure that is critical for driving membrane fusion and cell entry of HIV-1 (7)](https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7672035/#!po=11.3636)