title: [Studies of phosphorylation in rat mast cells (sixth report). Cyclic AMP-dependent protein phosphorylation in rat mast cell granule membranes].
abstract: Granules with broken membranes were isolated from sonicated, purified rat serosal mast cells on a Percoll gradient. When the granules were incubated with [gamma 32P]ATP and Mg2+ in the absence of exogenous protein kinases and substrates, one major radioactive band was recovered in the 44 K area after SDS/PAG electrophoresis. The phosphorylation reaction with ATP requires Mg2+ and 1 mM Mg2+ produces the maximal response. The initial reaction is rapid and the maximal response is seen at 30 degrees C. The reaction is enhanced by 0.05-0.5 microM cyclic AMP and is inhibited by Ca2+ (0.45 mM and higher). There is no obvious effect of phosphatidylserine and phorbol ester TPA on the reaction. The 44 K phosphorylated protein is made up of several components ranging in isoelectric point from approximately 7.6 to 6.6. This cyclic AMP-dependent phosphorylating activity in the granules may provide a mechanism by which the granules respond rapidly to cyclic AMP during mediator release.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D003594:Cytoplasmic Granules / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008407:Mast Cells / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D010718:Phosphatidylserines / Q000494:pharmacology; D010766:Phosphorylation; D011480:Protease Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D008565:Membrane Proteins; D010718:Phosphatidylserines; D011480:Protease Inhibitors; D011506:Proteins; D000242:Cyclic AMP; D008274:Magnesium; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium