Ion, was used as a negative control. The YU2(Dct) protein has a truncated cytoplasmic tail of 17 amino acids, with a stop codon introduced after Ala 710 (numbered according to current convention [46]). The YU2-GS8 construct is a cleavage-defective form of the YU2 HIV-1 envelope glycoproteins that contains an 8-amino acid glycine-serine linker at the gp120/gp41 junction. Starting with the cytoplasm