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. Degrades preferentially unfolded substrates in a processive, ATP-dependent manner, usually after hydrophobic residues. Binds 1 zinc ion per subunit. The proteolytic activity is dependent on ATP, both the ATPase and protease activities are inhibited by ADP. The isolated soluble domain (residues 126-624) forms a stable hexamer in which the AAA+ domains (residues 126-400) are alternatively open or closed. The open AAA+ domain (residues 126-400) probably allows nucleotide exchange and has the protease active site, while the closed domain is the active ATPase domain but the protease is inactive. In the central section; belongs to the AAA ATPase family. In the C-terminal section; belongs to the peptidase M41 family.