Cytochrome C is a small heme protein within the inner mitochondrial membrane responsible for carrying electrons within the respiratory transport chain. Additionally, cytochrome c has also been identified as a player in programmed cell death (apoptosis). During the early phases of apoptotic death reactions, cytochrome c translocates from the mitochondria membrane into the cytoplasm and serves to trigger the apoptotic proteolytic cascade by activating caspase 3, through association with protease activating factor-1 (Apaf-1).
