Figure 8.

Exogenous cytochrome c /dATP fails to promote caspase-3 processing within platelet lysates. Cytosolic extracts were treated with cytochrome c and dATP or buffer alone and incubated at 37°C. (a) Western blot analysis of platelet lysates revealed a failure of cytochrome c/dATP to promote the processing of caspase-3. (b) By contrast, Jurkat T cell lysates showed progressive processing of the enzyme to the proteolytically active p17/p12 fragments. (c) On addition of human recombinant caspase-9 and cytochrome c/dATP to fresh platelet lysates, derived from the same preparation used above, caspase-3 was now processed to its active p17/p12 subunits. Each Western blot had 50 μg of protein loaded per lane and was repeated twice.