The Ubiquitin proteasome System

The importance of the ubiquitin-proteasome system in cellular homoeostasis was emphasized by the award of the 2004 Nobel Prize in Chemistry to the discoverers of ubiquitin as a cofactor for intracellular non-lysosomal proteolysis. There is a voluminous literature showing that protein ubiquitylation and the degradation of ubiquitylated proteins by the 26 S proteasome controls almost every regulatory process in the cell. The contributors to this volume of Essays in Biochemistry focus on many different aspects of the role of the ubiquitin system in intracellular proteolysis, not only in cellular homoeostasis, but also in relation to disease. Ubiquitylation compliments and rivals protein phosphorylation/dephosphorylation in the regulation of cellular activities. Understanding the ubiquitin-proteasome system and related mechanisms will provide new therapeutic avenues in a variety of unrelated human diseases.