Fig. 6.

The ability of XIAP to bind cleaved effector caspases is inhibited by mutation of S40 to a phosphomimetic aspartate residue. HeLa S100 extract was incubated with cytochrome c and dATP to induce caspase cleavage prior to incubation with GFP–XIAP precipitated from cells stably expressing GFP–XIAP S40A or S40D protein. GFP–XIAP was recovered from the extract and co-precipitating proteins were detected by western blotting using the indicated antibodies. Cell lysates and HeLa cell S100 reactions were analysed for comparison.