Identification of the glycoprotein 41(TM) cytoplasmic tail domains of human immunodeficiency virus type 1 that interact with Pr55(Gag) particles

We investigated the protein/protein interactions that occur during human im munodeficiency virus (HIV-1) budding. We evaluated the binding to Pr55(Gag) particles of peptides mapping to the cytoplasmic tail of gp41(TM) and of h ost-cell proteins, in a cell-free, in vitro assay. Host-cell proteins and i rrelevant viral envelope peptides did not bind. Peptides corresponding to a large central domain of the gp41(TM) cytoplasmic tail (93 residues) bound to Pr55(Gag) particles. This demonstrates that a Gag/Env interaction is res ponsible for the specific incorporation of the Env glycoprotein into nascen t HIV-1 virions, and defines more accurately the gp41(TM) domain involved i n this interaction.