title: Possible involvement of protein phosphorylation in the regulation of the sulphonylurea receptor of a pancreatic beta-cell line, HIT T15.
abstract: The possible role of protein phosphorylation in modulation of [3H]glibenclamide binding to the sulphonylurea receptor, a putative ATP-sensitive K-channel, was investigated in the cloned pancreatic beta-cell line, HIT T15. Diazoxide, an opener of ATP-sensitive K-channels, increased HIT cell 86Rb-efflux, inhibited insulin secretion and decreased non-competitively [3H]glibenclamide binding to intact HIT cells. ATP-depletion reduced the [3H]glibenclamide binding activity of intact cells but did not change diazoxide-insensitive binding. Although diazoxide alone did not change the binding of [3H]glibenclamide to HIT cell membranes, the simultaneous presence of MgATP revealed an inhibition of [3H]glibenclamide binding by diazoxide. This effect of MgATP was reproduced by MgATP gamma S, but not by MgADP, MgAMP-PNP or MgAMP-PCP. These findings suggest that protein phosphorylation may be involved in the response of ATP-sensitive K-channels to diazoxide.
authors.affiliation: Nuffield Department of Clinical Biochemistry, John Radcliffe Hospital, Headington, Oxford, U.K.
authors.forename: I
authors.initials: I
authors.lastname: Niki
authors.forename: S J
authors.initials: SJ
authors.lastname: Ashcroft
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D018528:ATP-Binding Cassette Transporters; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D003981:Diazoxide / Q000494:pharmacology; D005905:Glyburide / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D047428:Protein Kinase Inhibitors; D011506:Proteins / Q000378:metabolism*; D011955:Receptors, Drug / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D064233:Sulfonylurea Receptors; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D007328:Insulin; D007546:Isoquinolines; D010879:Piperazines; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D047428:Protein Kinase Inhibitors; D011506:Proteins; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D005576:Colforsin; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D012413:Rubidium; D013755:Tetradecanoylphorbol Acetate; D003981:Diazoxide; D005905:Glyburide