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.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
-
ATP-Binding Cassette Transporters*
-
Adenosine Triphosphatases / metabolism
-
Adenosine Triphosphate / analogs & derivatives
-
Adenosine Triphosphate / metabolism
-
Animals
-
Cell Line
-
Cell Membrane / metabolism
-
Colforsin / pharmacology
-
Diazoxide / pharmacology
-
Glyburide / metabolism
-
Humans
-
Insulin / metabolism
-
Insulin Secretion
-
Islets of Langerhans / cytology
-
Islets of Langerhans / metabolism*
-
Isoquinolines / pharmacology
-
Phosphorylation
-
Piperazines / pharmacology
-
Potassium Channels / drug effects
-
Potassium Channels / metabolism*
-
Potassium Channels, Inwardly Rectifying*
-
Protein Kinase Inhibitors
-
Proteins / metabolism*
-
Receptors, Drug / metabolism*
-
Rubidium / metabolism
-
Sulfonylurea Receptors
-
Tetradecanoylphorbol Acetate / pharmacology
Substances
-
ATP-Binding Cassette Transporters
-
Insulin
-
Isoquinolines
-
Piperazines
-
Potassium Channels
-
Potassium Channels, Inwardly Rectifying
-
Protein Kinase Inhibitors
-
Proteins
-
Receptors, Drug
-
Sulfonylurea Receptors
-
Colforsin
-
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
-
Adenosine Triphosphate
-
Adenosine Triphosphatases
-
Rubidium
-
Tetradecanoylphorbol Acetate
-
Diazoxide
-
Glyburide