5igo
From Proteopedia
WD40 domain of Arabidopsis thaliana E3 Ubiquitin Ligase COP1 in complex with peptide from Trib1
Structural highlights
Function[COP1_ARATH] E3 ubiquitin-protein ligase that acts as a repressor of photomorphogenesis and as an activator of etiolation in darkness. 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. Represses photomorphogenesis in darkness by mediating ubiquitination and subsequent proteasomal degradation of light-induced transcription factors such as HY5, HYH and LAF1. Down-regulates MYB21, probably via ubiquitination process. Light stimuli abrogate the repression of photomorphogenesis, possibly due to its localization to the cytoplasm. Could play a role in switching between skotomorphogenetic and photomorphogenetic pathways.[1] [2] [TRIB1_HUMAN] Interacts with MAPK kinases and regulates activation of MAP kinases. May not display kinase activity.[3] [4] 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[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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