title: Calcium-dependent activation and deactivation of rod outer segment phosphodiesterase is calmodulin-independent.
abstract: ATP-dependent activation and deactivation of retinal rod outer segment phosphodiesterase is affected by calcium [Kawamura, S. and Bownds, M. D., J. Gen. Physiol. 77:571-591(1981)]. Our data demonstrate that although calmodulin has been found in rod outer segments [Liu, Y. P. and Schwartz, H., Biochim. Biophys. Acta 526:186-193(1978); Kohnken, R. E. et al, J. Biol. Chem. 256:12517-12522(1981)], this protein is not involved in calcium-dependent phosphodiesterase activation at light levels at which calcium clearly affects this enzyme's activity. Furthermore, calmodulin does not mediate the calcium-dependent deactivation of phosphodiesterase.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002417:Cattle; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000201:enzymology*; D012374:Rod Cell Outer Segment / Q000201:enzymology*; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D014268:Trifluoperazine; D010727:Phosphoric Diester Hydrolases; D002118:Calcium