Translation, Post-Translational Processing, and Mitochondrial Translocation of Yeast Iso-1-Cytochrome c
The complete biosynthesis and assembly of mitochondrial cytochrome c involves a number of steps, including the following: translation of the extramitochondrial precursor, apocytochrome c, on cytosolic ribosomes; excision of the amino-terminal methionine residue which is incorporated during initiation of translation of cytochrome c and of all other proteins; amino-terminal acetylation of vertebrate and plant cytochrome c and of certain mutant forms of yeast iso-1-cytochrome c; trimethylation of lysines 72 and 86 in plant cytochrome c and lysine 72 in fungal cytochrome c; binding of apocytochrome c to, presumably, a specific receptor on the outer mitochondrial membrane; the covalent attachment of protoheme to two cysteinyl residues, forming two thioether bonds; and the concomitant translocation across the outer mitochondrial membrane. These steps are schematically outlined in Fig. 1 for yeast iso-1-cytochrome c. We have been investigating all of these processes with mutant forms of yeast iso-1-cytochrome c and with cis-acting mutations that control these processes.
KeywordsMethionine Aminopeptidase Hairpin Loop Structure Yeast Cytochrome Cyc3 Mutant Penultimate Residue
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