ATP-dependent serine endopeptidases belong to MEROPS families S14 and S16 and catalyse the hydrolysis of proteins in the presence of ATP. They include the peptidase subunit of the Clp complex (S14 family) and the Lon protease (S16 family), which mediate the selective degradation of polypeptides in the mitochondrial matrix. (Adapted from FBrf0236413 and FBrf0240421.)