Protease component of the Clp complex that cleaves peptides and various proteins in an ATP-dependent process. Has low peptidase activity in the absence of CLPX. The Clp complex can degrade CSN1S1, CSN2 and CSN3, as well as synthetic peptides (in vitro) and may be responsible for a fairly general and central housekeeping function rather than for the degradation of specific substrates. Cleaves PINK1 in the mitochondrion. Hydrolysis of proteins to small peptides in the presence of ATP and magnesium. alpha-casein is the usual test substrate. In the absence of ATP, only oligopeptides shorter than five residues are hydrolyzed (such as succinyl-Leu-Tyr-|-NHMec, and Leu-Tyr-Leu-|-Tyr-Trp, in which cleavage of the -Tyr-|-Leu- and -Tyr-|-Trp bonds also occurs). Fourteen CLPP subunits assemble into 2 heptameric rings which stack back to back to give a disk-like structure with a central cavity. Component of the Clp complex formed by the assembly of two CLPP heptameric rings with two CLPX hexameric rings, giving rise to a symmetrical structure with two central CLPP rings flanked by a CLPX ring at either end of the complex. Belongs to the peptidase S14 family.