Identification of the glycoprotein 41TM cytoplasmic tail domains of human immunodeficiency virus type 1 that interact with Pr55Gag particles

We investigated the protein/protein interactions that occur during human immunodeficiency virus (HIV-1) budding. We evaluated the binding to Pr55(Gag) particles of peptides mapping to the cytoplasmic tail of gp41(TM) and of host-cell proteins, in a cell-free, in vitro assay. Host-cell proteins and irrelevant 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 responsible for the specific incorporation of the Env glycoprotein into nascent HIV-1 virions, and defines more accurately the gp41(TM) domain involved in this interaction.