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Publication Abstract from PubMed

Polyubiquitination is a posttranslational modification where ubiquitin chains containing isopeptide bonds linking one of seven ubiquitin lysines with the C terminus of an adjoining ubiquitin are covalently attached to proteins. While functions of K48- and K63-linked polyubiquitin are understood, the role(s) of noncanonical K11-linked chains is less clear. A crystal structure of K11-linked diubiquitin demonstrates a distinct conformation from K48- or K63-linked diubiquitin. We engineered a K11 linkage-specific antibody and use it to demonstrate that K11 chains are highly upregulated in mitotic human cells precisely when substrates of the ubiquitin ligase anaphase-promoting complex (APC/C) are degraded. These chains increased with proteasomal inhibition, suggesting they act as degradation signals in vivo. Inhibition of the APC/C strongly impeded the formation of K11-linked chains, suggesting that a single ubiquitin ligase is the major source of mitotic K11-linked chains. Our results underscore the importance of K11-linked ubiquitin chains as critical regulators of mitotic protein degradation.

K11-linked polyubiquitination in cell cycle control revealed by a K11 linkage-specific antibody.,Matsumoto ML, Wickliffe KE, Dong KC, Yu C, Bosanac I, Bustos D, Phu L, Kirkpatrick DS, Hymowitz SG, Rape M, Kelley RF, Dixit VM Mol Cell. 2010 Aug 13;39(3):477-84. Epub 2010 Jul 22. PMID:20655260^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.