title: Regulation of cAMP concentration by calmodulin-dependent cyclic nucleotide phosphodiesterase.
abstract: Bovine brain contains two major calmodulin (CaM) dependent phosphodiesterase isozymes which are homodimeric proteins with subunit molecular masses of 60 and 63 kilodaltons (kDa), respectively. The 60-kDa subunit isozyme can be phosphorylated by cAMP-dependent protein kinase, resulting in a decrease in the enzyme affinity towards CaM. The phosphorylation is blocked by Ca2+ and CaM and reversed by the CaM-stimulated phosphatase (calcineurin). The 63-kDa subunit isozymes can also be phosphorylated, but in this case by a CaM-dependent protein kinase(s). This phosphorylation is also accompanied by a decrease in the isozyme affinity towards CaM and can be reversed by the CaM-dependent phosphatase. Analysis of the complex regulatory properties of the phosphodiesterase isozymes has led to the suggestion that fluxes of cAMP and Ca2+ during cell activations are closely coupled and that the CaM-dependent phosphodiesterase isozymes play key roles in this signal coupling phenomenon.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism*; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D006706:Homeostasis; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010766:Phosphorylation
chemical_list: D007527:Isoenzymes; D046911:Macromolecular Substances; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1