Intracellular proteolysis: Signals of selective protein degradation

Selective proteolysis is one of the mechanisms for the maintenance of cell homeostasis via rapid degradation of defective polypeptides and certain sho rt-lived regulatory proteins. In prokaryotic cells, high-molecular-mass oli gomeric ATP-dependent proteases are responsible for selective protein degra dation. In eukaryotes, mast polypeptides are attacked by the multicatalytic 26S proteasome, and the degradation of the majority of substrates involves their preliminary modification with the protein ubiquitin. The proteins un dergoing the selective proteolysis often contain specific degradation signa ls necessary for their recognition by the corresponding proteases.