1kxu
From Proteopedia
CYCLIN H, A POSITIVE REGULATORY SUBUNIT OF CDK ACTIVATING KINASE
Structural highlights
Function[CCNH_HUMAN] Regulates CDK7, the catalytic subunit of the CDK-activating kinase (CAK) enzymatic complex. CAK activates the cyclin-associated kinases CDK1, CDK2, CDK4 and CDK6 by threonine phosphorylation. CAK complexed to the core-TFIIH basal transcription factor activates RNA polymerase II by serine phosphorylation of the repetitive C-terminus domain (CTD) of its large subunit (POLR2A), allowing its escape from the promoter and elongation of the transcripts. Involved in cell cycle control and in RNA transcription by RNA polymerase II. Its expression and activity are constant throughout the cell cycle.[1] [2] 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-dependent kinases (CDKs), which play a key role in cell cycle control, are activated by the CDK activating kinase (CAK), which activates cyclin-bound CDKs by phosphorylation at a specific threonine residue. Vertebrate CAK contains two key components: a kinase subunit with homology to its substrate CDKs and a regulatory subunit with homology to cyclins. We have determined the X-ray crystal structure of the regulatory subunit of CAK, cyclin H, at 2.6 A resolution. Cyclin H contains two alpha-helical core domains with a fold similar to that of cyclin A, a regulatory subunit of CAK substrate CDK2, and of TFIIB, a transcription factor. Outside of the core domains, the N- and C-terminal regions of the three structures are completely different. The conformational differences between cyclin H and A structures may reflect functional differences between the two cyclins. Three-dimensional structure of human cyclin H, a positive regulator of the CDK-activating kinase.,Kim KK, Chamberlin HM, Morgan DO, Kim SH Nat Struct Biol. 1996 Oct;3(10):849-55. PMID:8836101[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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