Niki I, Ashcroft S J
Nuffield Department of Clinical Biochemistry, John Radcliffe Hospital, Headington, Oxford, U.K.
Biochim Biophys Acta. 1991 Dec 3;1133(1):95-101. doi: 10.1016/0167-4889(91)90246-t.
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.
在克隆的胰腺β细胞系HIT T15中，研究了蛋白质磷酸化在调节[3H]格列本脲与磺酰脲受体（一种假定的ATP敏感性钾通道）结合中的可能作用。ATP敏感性钾通道开放剂二氮嗪增加了HIT细胞的86Rb外流，抑制了胰岛素分泌，并非竞争性地降低了[3H]格列本脲与完整HIT细胞的结合。ATP耗竭降低了完整细胞的[3H]格列本脲结合活性，但未改变二氮嗪不敏感的结合。尽管单独的二氮嗪不会改变[3H]格列本脲与HIT细胞膜的结合，但MgATP的同时存在显示二氮嗪对[3H]格列本脲结合有抑制作用。MgATPγS可重现MgATP的这种作用，但MgADP、MgAMP-PNP或MgAMP-PCP则不能。这些发现表明，蛋白质磷酸化可能参与了ATP敏感性钾通道对二氮嗪的反应。
