Human Cytochrome c (Human Heart Tissue) Protein, CF

Cytochrome c is a critical mitochondrial outer membrane-associated protein in the electron transport chain (1). Reduction and oxidation of an iron molecule (Fe³⁺ to Fe²⁺ and back) within its central heme group allow it to receive an electron from the Cytochrome c1 subunit of cytochrome reductase and pass it to cytochrome a within the cytochrome oxidase complex (1). Release of Cytochrome c from mitochondria occurs during initiation of apoptotic pathways, either by mechanisms that rupture or that do not rupture the mitochondial membrane (2, 3). Once in the cytosol, Cytochrome c forms a complex with procaspase 9, recruiting Apaf-1 (apoptotic protease activating factor-1) and dATP to form apoptosomes, which activate effector caspases and ultimately destroy the cell (2, 3). Cytochrome c is highly conserved, with 90% or greater amino acid identity among human (4), mouse, rat, cow and dog sequences. After Cytochrome c translation, the initial methionine is cleaved to form the 104 amino acid mature form.