The mitochondrial cytochrome c N-terminal region is critical for maturation by holocytochrome c synthase

► Mitochondrial holocytochrome c synthase recognises apocytochrome c N-terminus. ► N-terminus of yeast apocytochrome c/C-terminus of a bacterial cytochrome is processed. ► F15 of the N-terminus of yeast cytochrome c is essential for HCCS processing.