Effects of protein phosphorylation on the sulphonylurea receptor of the pancreatic beta-cell.

Abstract

There is evidence that protein phosphorylation may modulate the action of diazoxide on the β-cell K-ATP channel [1] and the sulphonylurea receptor [2–3]. In this paper, we have further investigated the role of phosphorylation in the action of diazoxide on the β-cell sulphonylurea receptor by carrying out time-course studies on inhibition of [3H]-gliben-clamide binding by MgATP and diazoxide, and by examining effects of phosphatase inhibitors on binding. We also investigated the presence of protein kinase and protein phosphatase activities in β-cell membrane fractions.