The central region of human immunodeficiency virus type 1 p6 protein (Gag residues S14-I31) is dispensable for the virus in vitro.

The human immunodeficiency virus type 1 p6 region encodes p6(Gag) and the transframe p6(Pol) protein. The Gag frame encodes an N-terminal late assembly L domain and a C-terminal Vpr binding domain. In the Pol frame, substitution at a C-terminal motif decreases protease autocleavage. The role of the highly polymorphic central region of p6, comprising amino acids S14-I31 (p6(Gag)) and R20-D39 (p6(Pol)), is unclear. Analysis of this central region demonstrated that 35 % of p6(Gag) appears to be dispensable for virus propagation in vitro and smaller deletion and insertion polymorphisms can be tolerated in vivo. Extensive Pol deletion (deltaR20-D39, 42 % of p6(Pol)) did not alter protease autocleavage.