Investigation of the role of Ca2+ and calmodulin in the regulation of platelet guanylate cyclase activity.
Both soluble and particulate forms of human platelet guanylate cyclase were found to be sensitive to sub-micromolar concentrations of free Ca2+; soluble enzyme activity increased as Ca2+ was increased from 10 nM to 1 microM; particulate enzyme activity showed a biphasic response to Ca2+, with maximal enzyme activity between 1 and 10 nM free Ca2+ and inhibition occurring at higher Ca2+ concentrations. Neither Ca2+-sensitivity appeared to be calmodulin-dependent.
D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003067:Coenzymes / Q000097:blood; D006162:Guanylate Cyclase / Q000097:blood*; D006801:Humans; D007811:Lanthanum / Q000494:pharmacology; D012995:Solubility; D013449:Sulfonamides / Q000494:pharmacology
D002147:Calmodulin; D003067:Coenzymes; D013449:Sulfonamides; C028521:lanthanum chloride; C017967:W 7; D007811:Lanthanum; D006162:Guanylate Cyclase; D002118:Calcium