Fig. 4. Mutagenic analysis of Tsg101 UEV binding to p6, p6–Ub and Ub. Biosensor binding isotherms are shown for putative PTAP-binding mutants (left) and Ub-binding mutants (right). Binding isotherms for p6 (top panels), p6–Ub (middle panels) and Ub (bottom panels) are shown. Mutants that significantly reduced p6 binding are shown in red, while those that significantly reduced Ub binding are shown in blue (see Table II). Mutations that had no significant effect are in green. Wild-type binding isotherms are in black.