Tissue heterogeneity of the mammalian mitochondrial proteome

The functionality of the mitochondrion is primarily determined by nuclear encoded proteins. The mitochondrial functional requirements of different tissues vary from a significant biosynthetic role (liver) to a primarily energy metabolism-oriented organelle (heart). The purpose of this study was to compare the mitochondrial proteome from four different tissues of the rat, brain, liver, heart, and kidney, to provide insight into the extent of mitochondrial heterogeneity and to further characterize the overall mitochondrial proteome. Mitochondria were isolated, solubilized, digested, and subjected to quantitative liquid chromatography-mass spectroscopy. Of the 16,950 distinct peptides detected, 8,045 proteins were identified. High-confidence identification threshold was reached by 1,162 peptides, which were further analyzed. Of these 1,162 proteins, 1,149 were significantly different in content (P and q values < 0.05) between at least 2 tissues, whereas 13 were not significantly different between any tissues...