Synthesis and assembly of cytochrome c oxidase in synchronous cultures of yeast

Does more than one mitochondrially synthesized protein in yeast have larger precursors?

Yeast cells undergoing derepression (the phase of mitochondriogenesis) were exposed to [14C]formate in the presence of cycloheximide, the cytosolic protein synthesis inhibitor, and of 1,10-phenanthroline, a metallo-protease inhibitor. Extensive labelling was obtained under such conditions. Incubation of these labelled products with mitochondrial lysates released small peptides (mol. wt. 500-1000). These results indicate that mitochondria probably synthesize some of the proteins in the precursor form and they are processed by a specific matrix-located protease before proper integration.