ACTIVATION OF CASPASES TRIGGERED BY CYTOCHROME-C IN-VITRO

Previous studies hare shown that Apaf-1 and caspase-9 in the presence of cytochrome c and dATP can form an initiating complex for an apoptot ic protease cascade. We have developed a cytochrome c-dependent in vit ro system in which caspases downstream of this initiation complex are activated. The activation of caspase-9 from zymogen form to active dim eric protease requires intrinsic enzymatic activity, In contrast, casp ase-3 and caspase-7 zymogens are proteolytically processed by active c aspase-9, Activation of the above caspases is blocked by a dominant ne gative form of caspase-9, The in vitro system displays surprising spec ificity in that other caspases, including 1, 2, 4, 8, 10, and 13, are not activated. (C) 1998 Federation of European Biochemical Societies.