Figure 4.

cIAP1R-Ub^D interactions. A, cartoon representation of the catalytic competent cIAP1R dimer bound to UbcH5B–Ub (left) and close-up view of cIAP1R-Ub^D interactions (right). All coloring is the same as in Fig. 2. Hydrogen bonds are shown as dotted lines. B, nonreduced SDS-PAGE of lysine discharge reactions showing the disappearance of UbcH5B∼Ub band over time catalyzed by cIAP1R variants. C, nonreduced SDS-PAGE of lysine discharge reactions showing the disappearance of UbcH5B∼Ub variant bands over time catalyzed by cIAP1R. *, contaminating band from other reaction components.