ISSN:
1432-5233
Keywords:
Key words Protein phosphatase
;
Sulfonylurea
;
Protein phosphorylation
;
Intracellular signals
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract We have measured protein phosphatase (PP) activity in crude homogenates as well as in the total 105,000×g supernatant and precipitate fractions from normal rat pancreatic islets. On the basis of the inhibition produced by either 1 nM or 1 µM okadaic acid, both PP1 and PP2A activity were present in crude islet homogenates in equivalent proportions (53% and 47%, respectively); PP1 was the main activity present in the precipitate, whereas in the supernatant it was PP2A. Tolbutamide, glybenclamide and glyclazide significantly decreased PP activity in islet homogenates in a dose-dependent manner, with a K i0.5 value that in the case of glybenclamide correlated with its K d for binding site, its EC50 on KATP channel, and its EC50 on insulin release. These data indicate that PPs play a role in the control of insulin secretion and suggest a further possible target for sulfonylureas within their overall action as insulin secretagogues.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s005920050057
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