PROTEASOMES - PROTEASE COMPLEXES LEAD TO A NEW UNDERSTANDING OF CELLULAR-REGULATION VIA PROTEOLYSIS

Proteasomes are large multicatalytic protease complexes which fulfill central functions in major proteolytic pathways of the eukaryotic cell . Two types of proteasomes are known: the cylindrically shaped 20S pro teasome (700 kDa) and the 26S proteasome (1700 kDa) which contains the 20S proteasome as a functional core. Proteasomes are needed for stres s-dependent and ubiquitin-mediated proteolysis. They are involved in d egradation of abnormal, short-lived, and regulatory proteins. Proteaso mes are important for cell differentiation and adaptation to environme ntal changes. Proteasomes have been shown to function in the control o f the cell cycle and are suggested to be involved in antigen presentat ion by processing of intracellular proteins to antigenic peptides.