Chemical Tools To Study the Proteasome

Proteolysis, or the processing and degradation of proteins, has emerged as one of the most widely studied processes in biology today. Long viewed as a dead end process, of importance only for the removal of obsolete peptides and proteins, proteolytic events are now associated with numerous biological events. The main proteolytic pathway in the eukaryotic cytoplasm and nucleus, responsible for the degradation of 80-90% of all cellular proteins is known as the Ubiquitin Proteasome System (UPS). Proteasomes are the central proteases in this tightly controlled ATP- and ubiquitin-dependent proteolytic pathway. Proteasomes are multicatalytic, compartmentalized proteinase complexes. Their substrates include abnormal and damaged proteins, cell-cycle regulators, oncogens and tumor suppressors. Furthermore, proteasomal degradation is imperative for the generation of MHC class I antigenic peptides. The recent approval of a proteasome inhibitor as a cancer drug has boosted proteasome research. This microreview highlights the recent advances in the development of chemical tools to study proteasome activity. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)