Structural highlights
FunctionUBE4B_HUMAN Binds to the ubiquitin moieties of preformed conjugates and catalyzes ubiquitin chain assembly in conjunction with E1, E2, and E3 (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHuman E4B, also called UFD2a, is a U box-containing protein that functions as an E3 ubiquitin ligase and an E4 polyubiquitin chain elongation factor. E4B is thought to participate in the proteasomal degradation of misfolded or damaged proteins through association with chaperones. The U box domain is an anchor site for E2 ubiquitin-conjugating enzymes, but little is known of the binding mechanism. Using X-ray crystallography and NMR spectroscopy, we determined the structures of E4B U box free and bound to UbcH5c and Ubc4 E2s. Whereas previously characterized U box domains are homodimeric, we show that E4B U box is a monomer stabilized by a network of hydrogen bonds identified from scalar coupling measurements. These structural studies, complemented by calorimetry- and NMR-based binding assays, suggest an allosteric regulation of UbcH5c and Ubc4 by E4B U box and provide a molecular basis to understand how the ubiquitylation machinery involving E4B assembles. Molecular basis for the association of human E4B U box ubiquitin ligase with E2-conjugating enzymes UbcH5c and Ubc4.,Benirschke RC, Thompson JR, Nomine Y, Wasielewski E, Juranic N, Macura S, Hatakeyama S, Nakayama KI, Botuyan MV, Mer G Structure. 2010 Aug 11;18(8):955-65. PMID:20696396[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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