Regulation via the Ubiquitin-Proteasome Pathway

Proteolysis is a versatile tool in the cell for the targeted change in structure, activity, function and subcellular distribution of proteins. 

Only the targeted degradation of proteins will be discussed in the following. For the maturation of proteins and for proteolysis by classical proteases the reader is referred to biochemical textbooks. 

The nonlysosomal degradation pathways allow for the selective degradation of proteins under normal cellular conditions. These degradation pathways are also respon- 

Life span (h) Nucleus Cytosol ER and plasma membrane 

2-8 Cyclins Protein kinase A Tryptophan oxygenase y-Glutamyl transferase 

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Huang, L.E., J. Gu, M. Schau, and H.F. Bunn (1998). Regulation of hypoxia-inducible factor 1 alpha is mediated by an 02-dependent degradation domain via the ubiquitin-proteasome pathway. Proc. Natl. Acad. Sci. USA 95 7987-7992. 

Upon an external signal, the phosphorylation of NFkB is induced, whereby the inhibitor complex is broken up. The inhibitor IkB is degraded via the ubiquitin-proteasome pathway, while the phos-phorylated NFkB is transported to the nucleus where it can fulfill its transcription regulation function. 

Huang LE, Gu J, Schau M, Bunn HF. Regulation of h3tpoxia-inducible factor la is mediated by an oxygen-dependent domain via the ubiquitin-proteasome pathway. Proc Natl Acad Sci USA 1998 95 7987-7992. 

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