1zp2
From Proteopedia
Structure of the Mediator subunit cyclin C
Structural highlights
Function[SRB11_SCHPO] Component of the Cdk8 module/Srb8-11 module which is a regulatory module of the Mediator complex that regulates basal RNA polymerase II transcription. The Cdk8 module may sterically hinder the interaction between Mediator and RNA polymerase II leading to transcriptional repression of a subset of genes regulated by Mediator. 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 PubMedCyclin C binds the cyclin-dependent kinases CDK8 and CDK3, which regulate mRNA transcription and the cell cycle, respectively. The crystal structure of cyclin C reveals two canonical five-helix repeats and a specific N-terminal helix. In contrast to other cyclins, the N-terminal helix is short, mobile, and in an exposed position that allows for interactions with proteins other than the CDKs. A model of the CDK8/cyclin C pair reveals two regions in the interface with apparently distinct roles. A conserved region explains promiscuous binding of cyclin C to CDK8 and CDK3, and a non-conserved region may be responsible for discrimination of CDK8 against other CDKs involved in transcription. A conserved and cyclin C-specific surface groove may recruit substrates near the CDK8 active site. Activation of CDKs generally involves phosphorylation of a loop at a threonine residue. In CDK8, this loop is longer and the threonine is absent, suggesting an alternative mechanism of activation that we discuss based on a CDK8-cyclin C model. Structure of the mediator subunit cyclin C and its implications for CDK8 function.,Hoeppner S, Baumli S, Cramer P J Mol Biol. 2005 Jul 29;350(5):833-42. PMID:15979093[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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