5aiu
From Proteopedia
A complex of RNF4-RING domain, Ubc13-Ub (isopeptide crosslink)
Structural highlights
FunctionRNF4_RAT E3 ubiquitin-protein ligase which binds polysumoylated chains covalently attached to proteins and mediates 'Lys-6'-, 'Lys-11'-, 'Lys-48'- and 'Lys-63'-linked polyubiquitination of those substrates and their subsequent targeting to the proteasome for degradation. Regulates the degradation of several proteins including PML and the transcriptional activator PEA3. Involved in chromosome alignment and spindle assembly, it regulates the kinetochore CENPH-CENPI-CENPK complex by targeting polysumoylated CENPI to proteasomal degradation. Regulates the cellular responses to hypoxia and heat shock through degradation of respectively EPAS1 and PARP1. Alternatively, it may also bind DNA/nucleosomes and have a more direct role in the regulation of transcription for instance enhancing basal transcription and steroid receptor-mediated transcriptional activation.[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedRING E3 ligase-catalyzed formation of K63-linked ubiquitin chains by the Ube2V2-Ubc13 E2 complex is required in many important biological processes. Here we report the structure of the RING-domain dimer of rat RNF4 in complex with a human Ubc13 approximately Ub conjugate and Ube2V2. The structure has captured Ube2V2 bound to the acceptor (priming) ubiquitin with K63 in a position favorable for attack on the linkage between Ubc13 and the donor (second) ubiquitin held in the active 'folded back' conformation by the RING domain of RNF4. We verified the interfaces identified in the structure by in vitro ubiquitination assays of site-directed mutants. To our knowledge, this represents the first view of synthesis of K63-linked ubiquitin chains in which both substrate ubiquitin and ubiquitin-loaded E2 are juxtaposed to allow E3 ligase-mediated catalysis. Structural basis for the RING-catalyzed synthesis of K63-linked ubiquitin chains.,Branigan E, Plechanovova A, Jaffray EG, Naismith JH, Hay RT Nat Struct Mol Biol. 2015 Jul 6. doi: 10.1038/nsmb.3052. PMID:26148049[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also
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