1ldd | pdb_00001ldd
Structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF Ubiquitin Ligase Complex
Structural highlights
Function[APC2_YEAST] Component of the anaphase promoting complex/cyclosome (APC/C), a cell cycle-regulated E3 ubiquitin-protein ligase complex that controls progression through mitosis and the G1 phase of the cell cycle. The APC/C is thought to confer substrate specificity and, in the presence of ubiquitin-conjugating E2 enzymes, it catalyzes the formation of protein-ubiquitin conjugates that are subsequently degraded by the 26S proteasome. In early mitosis, the APC/C is activated by CDC20 and targets securin PDS1, the B-type cyclin CLB5, and other anaphase inhibitory proteins for proteolysis, thereby triggering the separation of sister chromatids at the metaphase-to-anaphase transition. In late mitosis and in G1, degradation of CLB5 allows activation of the APC/C by CDH1, which is needed to destroy CDC20 and the B-type cyclin CLB2 to allow exit from mitosis and creating the low CDK state necessary for cytokinesis and for reforming prereplicative complexes in G1 prior to another round of replication.[1] 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 PubMedSCF complexes are the largest family of E3 ubiquitin-protein ligases and mediate the ubiquitination of diverse regulatory and signalling proteins. Here we present the crystal structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF complex, which shows that Cul1 is an elongated protein that consists of a long stalk and a globular domain. The globular domain binds the RING finger protein Rbx1 through an intermolecular beta-sheet, forming a two-subunit catalytic core that recruits the ubiquitin-conjugating enzyme. The long stalk, which consists of three repeats of a novel five-helix motif, binds the Skp1-F boxSkp2 protein substrate-recognition complex at its tip. Cul1 serves as a rigid scaffold that organizes the Skp1-F boxSkp2 and Rbx1 subunits, holding them over 100 A apart. The structure suggests that Cul1 may contribute to catalysis through the positioning of the substrate and the ubiquitin-conjugating enzyme, and this model is supported by Cul1 mutations designed to eliminate the rigidity of the scaffold. Structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF ubiquitin ligase complex.,Zheng N, Schulman BA, Song L, Miller JJ, Jeffrey PD, Wang P, Chu C, Koepp DM, Elledge SJ, Pagano M, Conaway RC, Conaway JW, Harper JW, Pavletich NP Nature. 2002 Apr 18;416(6882):703-9. PMID:11961546[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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