title: Does calmodulin mediate inhibition of human erythrocyte Ca(2+)-pumping ATPase by myricetin?
abstract: Myricetin, a flavonoid, potently inhibits human erythrocyte plasma membrane Ca(2+)-pumping ATPase activity: half-maximal inhibition of the basal and calmodulin-stimulated activity is obtained with 6 microM myricetin. Inhibition of the Ca(2+)-ATPase by myricetin is observed at all concentrations of free Ca2+ from 10(-8)M to 10(-5)M. The extent of inhibition of the Ca(2+)-ATPase is dependent on the time of preincubation of the plasma membranes with myricetin. Inhibition of the Ca(2+)-ATPase by myricetin is not reversed by excess calmodulin. It is concluded that calmodulin does not mediate myricetin's inhibition of human erythrocyte plasma membrane Ca(2+)-pumping ATPase.
authors.affiliation: Department of Biochemistry, National University of Singapore, Kent Ridge.
authors.forename: T S
authors.initials: TS
authors.lastname: Teo
authors.forename: P
authors.initials: P
authors.lastname: Thiyagarajah
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Wong
authors.forename: N P
authors.initials: NP
authors.lastname: Das
mesh_terms: D000906:Antibodies; D002118:Calcium / Q000097:blood; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000097:blood*; D002147:Calmodulin / Q000097:blood* / Q000276:immunology / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000201:enzymology*; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics
chemical_list: D000906:Antibodies; D002147:Calmodulin; D005419:Flavonoids; D004533:Egtazic Acid; C040015:myricetin; D000252:Calcium-Transporting ATPases; D002118:Calcium