26S proteasome
Jump to navigation
Jump to search
Function
- multicatalytic proteinase complex
- along with macro-autophagy, facilitates one of two major degradation pathways
- has an ATP-dependent proteolytic activity
- cleavage of peptide bonds with very broad specificity
- cleaves peptides with Arg, Phe, Tyr, Leu, & Glu adjacent to the leaving group at neutral or slightly basic pH
- tyrosine phosphorylation of specific subunits of proteasomes may enhance translocation into the nucleus
- the proteasome is refered to as an organelle involved in ubiquitin-mediated degradation of proteins[2]
- the ubiquitin-proteasome system is NOT able to breakdown muscle fibril proteins.[2]
Structure
- composed of at least 15 non identical subunits which form a highly ordered ring-shaped structure
- two 19S regulatory caps at the end of the 20S proteasome barrel form the 26S proteasome.[5]
- the 19S caps mediate recognition of polyubiquitin & unfold the target protein for degradation
- the unfolded protein is fed into the 20S proteasome chamber for proteolysis.[5]
More general terms
Additional terms
References
- ↑ Tanaka K, Yoshimura T, Tamura T, Fujiwara T, Kumatori A, Ichihara A. Possible mechanism of nuclear translocation of proteasomes. FEBS Lett. 1990 Oct 1;271(1-2):41-6. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/2226812
- ↑ 2.0 2.1 2.2 Allende JE, Allende CC. Protein kinases. 4. Protein kinase CK2: an enzyme with multiple substrates and a puzzling regulation. FASEB J. 1995 Mar;9(5):313-23. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/7896000
- ↑ Tidball J, 9th Annual UCLA Research Conference on Aging, June 17, 2004 (conference speaker)
- ↑ PROSITE :accession PS00674
- ↑ 5.0 5.1 5.2 Kosik KS, Shimura H. Phosphorylated tau and the neurodegenerative foldopathies. Biochim Biophys Acta. 2005 Jan 3;1739(2-3):298-310. Epub 2004 Nov 26. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/15615647