5hqg
From Proteopedia
WD40 domain of Human E3 Ubiquitin Ligase COP1 (RFWD2)
Structural highlights
FunctionCOP1_HUMAN E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of target proteins. E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates. Involved in JUN ubiquitination and degradation. Directly involved in p53 (TP53) ubiquitination and degradation, thereby abolishing p53-dependent transcription and apoptosis. Ubiquitinates p53 independently of MDM2 or RCHY1. Probably mediates E3 ubiquitin ligase activity by functioning as the essential RING domain subunit of larger E3 complexes. In contrast, it does not constitute the catalytic RING subunit in the DCX DET1-COP1 complex that negatively regulates JUN, the ubiquitin ligase activity being mediated by RBX1. Involved in 14-3-3 protein sigma/SFN ubiquitination and proteasomal degradation, leading to AKT activation and promotion of cell survival. Ubiquitinates MTA1 leading to its proteasomal degradation. Upon binding to TRIB1, ubiquitinates CEBPA, which lacks a canonical COP1-binding motif (Probable).[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedCOP1 proteins are E3 ubiquitin ligases that regulate phototropism in plants and target transcription factors for degradation in mammals. The substrate-binding region of COP1 resides within a WD40-repeat domain that also binds to Trib proteins, which are adaptors for C/EBPalpha degradation. Here we report structures of the human COP1 WD40 domain in isolation, and complexes of the human and Arabidopsis thaliana COP1 WD40 domains with the binding motif of Trib1. The human and Arabidopsis WD40 domains are seven-bladed beta propellers with an inserted loop on the bottom face of the first blade. The Trib1 peptide binds in an extended conformation to a highly conserved surface on the top face of the beta propeller, indicating a general mode for recognition of peptide motifs by COP1. Together, these studies identify the structural basis and key interactions for motif recognition by COP1, and hint at how Trib1 autoinhibition is overcome to target C/EBPalpha for degradation. Structural Basis for Substrate Selectivity of the E3 Ligase COP1.,Uljon S, Xu X, Durzynska I, Stein S, Adelmant G, Marto JA, Pear WS, Blacklow SC Structure. 2016 May 3;24(5):687-96. doi: 10.1016/j.str.2016.03.002. Epub 2016 Mar, 31. PMID:27041596[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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