Regulation of mitochondrial proteolysis. Selective degradation of inner membrane polypeptides.

The in vitro degradation of respiratory chain polypeptide components by a proteinase associated with the intermembrane space fraction was studied in rat liver mitochondria. Differences in susceptibility to proteolysis were detected by gel analysis after electrophoretic separation of the degraded polypeptides. A 55 kDa subunit is protected from proteolysis by the ATP molecule.