SDH5, a gene required for flavination of succinate dehydrogenase, is mutated in paraganglioma

Tapping the Mitochondrial Proteome Mitochondria produce the energy that cells need to survive, function, and divide. A growing list of human disorders has been traced to defects in mitochondrial function. About 300 mammalian mitochondrial proteins are functionally uncharacterized, and Hao et al. (p. 1139 , published online 23 July) reasoned that the most highly conserved proteins within this group might provide insights into human disease. A combination of bioinformatics, yeast genetics, biochemistry, and human genetics was used to show that a previously uncharacterized mitochondrial protein (Sdh5) is required for the activity of respiratory complex II. Inactivating mutations in the human gene encoding SDH5 were found in individuals with hereditary paraganglioma, a rare neuroendocrine tumor. Thus, analysis of a mitochondrial protein in yeast has revealed a human tumor susceptibility gene.