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ORTHORHOMBIC COMPLEX STRUCTURE OF HUMAN PROTEIN KINASE CK2 CATALYTIC SUBUNIT (ISOFORM CK2ALPHA') WITH THE INHIBITOR 4'-CARBOXY-6,8-CHLORO- FLAVONOL (FLC21)
Structural highlights
FunctionCSK22_HUMAN Catalytic subunit of a constitutively active serine/threonine-protein kinase complex that phosphorylates a large number of substrates containing acidic residues C-terminal to the phosphorylated serine or threonine. Regulates numerous cellular processes, such as cell cycle progression, apoptosis and transcription, as well as viral infection. May act as a regulatory node which integrates and coordinates numerous signals leading to an appropriate cellular response. During mitosis, functions as a component of the p53/TP53-dependent spindle assembly checkpoint (SAC) that maintains cyclin-B-CDK1 activity and G2 arrest in response to spindle damage. Also required for p53/TP53-mediated apoptosis, phosphorylating 'Ser-392' of p53/TP53 following UV irradiation. Can also negatively regulate apoptosis. Phosphorylates the caspases CASP9 and CASP2 and the apoptotic regulator NOL3. Phosphorylation protects CASP9 from cleavage and activation by CASP8, and inhibits the dimerization of CASP2 and activation of CASP8. Regulates transcription by direct phosphorylation of RNA polymerases I, II, III and IV. Also phosphorylates and regulates numerous transcription factors including NF-kappa-B, STAT1, CREB1, IRF1, IRF2, ATF1, SRF, MAX, JUN, FOS, MYC and MYB. Phosphorylates Hsp90 and its co-chaperones FKBP4 and CDC37, which is essential for chaperone function. Regulates Wnt signaling by phosphorylating CTNNB1 and the transcription factor LEF1. Acts as an ectokinase that phosphorylates several extracellular proteins. During viral infection, phosphorylates various proteins involved in the viral life cycles of EBV, HSV, HBV, HCV, HIV, CMV and HPV.[1] [2] [3] Publication Abstract from PubMedProtein kinase CK2 is associated with a number of human diseases, among them cancer, and is therefore a target for inhibitor development in industry and academia. Six crystal structures of either CK2alpha, the catalytic subunit of human protein kinase CK2, or its paralog CK2alpha' in complex with two ATP-competitive inhibitors-based on either a flavonol or a thieno[2,3-d]pyrimidine framework-are presented. The structures show examples for extreme structural deformations of the ATP-binding loop and its neighbourhood and of the hinge/helix alphaD region, i.e., of two zones of the broader ATP site environment. Thus, they supplement our picture of the conformational space available for CK2alpha and CK2alpha'. Further, they document the potential of synthetic ligands to trap unusual conformations of the enzymes and allow to envision a new generation of inhibitors that stabilize such conformations. Structural Hypervariability of the Two Human Protein Kinase CK2 Catalytic Subunit Paralogs Revealed by Complex Structures with a Flavonol- and a Thieno[2,3-d]pyrimidine-Based Inhibitor.,Niefind K, Bischoff N, Golub AG, Bdzhola VG, Balanda AO, Prykhod'ko AO, Yarmoluk SM Pharmaceuticals (Basel). 2017 Jan 11;10(1). pii: E9. doi: 10.3390/ph10010009. PMID:28085026[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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