Cytochrome c is released in a single step during apoptosis
Cell Death and Differentiation
Release of cytochrome c from mitochondria is a central event in apoptotic signaling. In this study, we utilized a cytochrome c fusion that binds fluorescent biarsenical ligands (cytochrome c-4CYS (cyt. c-4CYS)) as well as cytochrome c-green fluorescent protein (cyt. c-GFP) to measure its release from mitochondria in different cell types during apoptosis. In single cells, the kinetics of cyt. c-4CYS release was indistinguishable from that of cyt. c-GFP in apoptotic cells expressing both
... ssing both molecules. Lowering the temperature by 71C did not affect this corelease, but further separated cytochrome c release from the subsequent decrease in mitochondrial membrane potential (DW m ). Cyt. c-GFP rescued respiration in cells lacking endogenous cytochrome c, and the duration of cytochrome c release was approximately 5 min in a variety of cell types induced to die by various forms of cellular stress. In addition, we could observe no evidence of caspase-dependent amplification of cytochrome c release or changes in DW m preceding the release of cyt. c-GFP. We conclude that there is a general mechanism responsible for cytochrome c release that proceeds in a single step that is independent of changes in DW m .