Acts as a processive, ATP-dependent zinc metallopeptidase for both cytoplasmic and membrane proteins. Plays a role in the quality control of integral membrane proteins. Binds 1 zinc ion per subunit. The isolated ADP-bound cytosolic domain forms a 6-fold symmetric protease disk and a 2-fold symmetric AAA ATPase ring. In the absence of nucleotide the AAA ATPase ring also forms symmetric hexamers. In the central section; belongs to the AAA ATPase family. In the C-terminal section; belongs to the peptidase M41 family.