title: cAMP, not Ca2+/calmodulin, regulates the phosphorylation of acetylcholine receptor in Torpedo californica electroplax.
abstract: The regulation of the phosphorylation of the acetylcholine receptor in electroplax membranes from Torpedo californica and of purified acetylcholine receptor was investigated. The phosphorylation of the membrane-bound acetylcholine receptor was not stimulated by Ca2+/calmodulin, nor was it inhibited by EGTA, but it was stimulated by the catalytic subunit of cAMP-dependent protein kinase, and was blocked by the protein inhibitor of cAMP-dependent protein kinase. Purified acetylcholine receptor was not phosphorylated by Ca2+/calmodulin-dependent protein kinase activity in electroplax membranes, nor by partially purified Ca2+/calmodulin-dependent protein kinases from soluble or particulate fractions from the electroplax. Of the four acetylcholine receptor subunits, termed alpha, beta, gamma and delta, only the gamma- and delta-subunits were phosphorylated by the cAMP-dependent protein kinase (+ cAMP), or by its purified catalytic subunits.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D000242:Cyclic AMP / Q000378:metabolism*; D004557:Electric Organ / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism*; D014101:Torpedo
chemical_list: D002147:Calmodulin; D011950:Receptors, Cholinergic; D000242:Cyclic AMP; D011494:Protein Kinases; D002118:Calcium