1c8k

FLAVOPIRIDOL INHIBITS GLYCOGEN PHOSPHORYLASE BY BINDING AT THE INHIBITOR SITE

spinqualitylabelsall models 1c8k, resolution 1.76Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1c8k is a 1 chain structure with sequence from Oryctolagus cuniculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CPB, PLP Activity: Phosphorylase, with EC number 2.4.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [PYGM_RABIT] Phosphorylase is an important allosteric enzyme in carbohydrate metabolism. Enzymes from different sources differ in their regulatory mechanisms and in their natural substrates. However, all known phosphorylases share catalytic and structural properties. 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 PubMed Flavopiridol (L86-8275) ((-)-cis-5, 7-dihydroxy-2-(2-chlorophenyl)-8-[4-(3-hydroxy-1-methyl)-piperidinyl] -4H-benzopyran-4-one), a potential antitumor drug, currently in phase II trials, has been shown to be an inhibitor of muscle glycogen phosphorylase (GP) and to cause glycogen accumulation in A549 non-small cell lung carcinoma cells (Kaiser, A., Nishi, K., Gorin, F.A., Walsh, D.A., Bradbury, E. M., and Schnier, J. B., unpublished data). Kinetic experiments reported here show that flavopiridol inhibits GPb with an IC(50) = 15.5 microm. The inhibition is synergistic with glucose resulting in a reduction of IC(50) for flavopiridol to 2.3 microm and mimics the inhibition of caffeine. In order to elucidate the structural basis of inhibition, we determined the structures of GPb complexed with flavopiridol, GPb complexed with caffeine, and GPa complexed with both glucose and flavopiridol at 1.76-, 2.30-, and 2.23-A resolution, and refined to crystallographic R values of 0.216 (R(free) = 0.247), 0.189 (R(free) = 0.219), and 0.195 (R(free) = 0.252), respectively. The structures provide a rational for flavopiridol potency and synergism with glucose inhibitory action. Flavopiridol binds at the allosteric inhibitor site, situated at the entrance to the catalytic site, the site where caffeine binds. Flavopiridol intercalates between the two aromatic rings of Phe(285) and Tyr(613). Both flavopiridol and glucose promote the less active T-state through localization of the closed position of the 280s loop which blocks access to the catalytic site, thereby explaining their synergistic inhibition. The mode of interactions of flavopiridol with GP is different from that of des-chloro-flavopiridol with CDK2, illustrating how different functional parts of the inhibitor can be used to provide specific and potent binding to two different enzymes. Flavopiridol inhibits glycogen phosphorylase by binding at the inhibitor site.,Oikonomakos NG, Schnier JB, Zographos SE, Skamnaki VT, Tsitsanou KE, Johnson LN J Biol Chem. 2000 Nov 3;275(44):34566-73. PMID:10924512 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glycogen Phosphorylase

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