Plasma membrane of pancreatic islets contains a calcium sensitive phosphatidylinositol
kinase. This enzyme catalyzes the first reaction in the pathway leading to the production
of inositol trisphosphate, which is believed to cause a redistribution of intracellular
calcium. Since the activity of this enzyme is inhibited by calcium (K0.5 = 10 μM),a loss of calcium from plasma membrane (the site of PI kinase) may be necessary
for activation of the enzyme in vivo.
Pancreatic Islets
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Rat
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Phosphatidylinositol
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Phosphatidylinositol Kinase
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Calcium Inhibition
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Plasma Membrane
