Activation of protein kinase C by a tumor‐promoting phorbol ester in pancreatic islets
Open Access
- 21 May 1984
- journal article
- Published by Wiley in FEBS Letters
- Vol. 170 (2) , 247-253
- https://doi.org/10.1016/0014-5793(84)81322-8
Abstract
Rat pancreatic islet homogenates display protein kinase C activity. This phospholipid‐dependent and calcium‐sensitive enzyme is activated by diacylglycerol or the tumor‐promoting phorbol ester 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). In the presence of TPA, the K a for Ca2+ is close to 5 μM. TPA does not affect phosphoinositide turnover but stimulates [32P]‐ and [3H]choline‐labelling of phosphatidylcholine in intact islets. Exogenous phospholipase C stimulates insulin release, in a sustained and glucose‐independent fashion. The secretory response to phospholipase C persists in media deprived of CaCl2. It is proposed that protein kinase C participates in the coupling of stimulus recognition to insulin release evoked by TPA, phospholipase C and, possibly, those secretatogues causing phosphoinositide breakdown in pancreatic islets.Keywords
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