Abstract
Mastoparan inhibited [3H]inositol phosphate accumulation induced by carbachol as well as cyclic AMP accumulation induced by isoproterenol in 1321N1 human astrocytoma cells. Mastoparan inhibited GTP gamma S-induced, but not Ca2(+)-induced, [3H]inositol phosphate accumulation in membrane preparations with an IC50 of approximately 10 microM. The inhibitory effect of mastoparan on carbachol-induced [3H]inositol phosphate accumulation was resistant to pertussis toxin (IAP) treatment in intact cells. These results suggest that mastoparan inhibits phospholipase C in human astrocytoma cells via a GTP binding protein, which is not a substrate for IAP.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Astrocytoma / enzymology
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Astrocytoma / metabolism*
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Bee Venoms / pharmacology*
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Calcium / pharmacology
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Cyclic AMP / metabolism
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Dose-Response Relationship, Drug
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GTP-Binding Proteins / pharmacology*
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Guanosine Triphosphate / antagonists & inhibitors
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Guanosine Triphosphate / pharmacology
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Humans
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Hydrolysis
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Inositol Phosphates / metabolism
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Intercellular Signaling Peptides and Proteins
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Peptides
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Pertussis Toxin
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Phosphatidylinositols / metabolism*
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Tumor Cells, Cultured / drug effects
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Type C Phospholipases / antagonists & inhibitors
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Virulence Factors, Bordetella / pharmacology
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Wasp Venoms / antagonists & inhibitors
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Wasp Venoms / pharmacology*
Substances
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Bee Venoms
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Inositol Phosphates
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Intercellular Signaling Peptides and Proteins
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Peptides
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Phosphatidylinositols
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Virulence Factors, Bordetella
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Wasp Venoms
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mastoparan
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Guanosine Triphosphate
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Cyclic AMP
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Pertussis Toxin
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Type C Phospholipases
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GTP-Binding Proteins
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Calcium