Within cells misfoldes and/or short-lived regulatory proteins are degrades by protease
machines, multi-subunit assemblages with form cages. Their proteolytic active sites are sequestered inside the particles and located on the inner walls. Access of protein substrates occurs in a precisely regulated manner. Regulation may be ATP-dependant or independent by protein subcomplexes or protein domains which also may have chaperone activity. Four protease machines will be described displaying different oligomeric states, subunit structures, enzymatic mechanisms, and regulatory properties.