Tolerance of diverse amino acid substitutions at conserved positions in the nuclear export signal (NES) of HIV-1 Rev.

The effector domain of the Rev protein is a nuclear export signal (NES) that is responsible for transporting Rev and its bound congeners out of the nucleus and into the cytoplasm. Previous work has identified several critical residues in the NES and has led to the belief that NESs of the Rev type are necessarily leucine rich. Here we present the sequences of a large number of functional Rev molecules with NES mutations. The data indicate a previously unreported diversity in allowable residues at a number of positions, including each of the leucine residues previously considered essential.