Photoaffinity labeling with GTP-gamma-azidoanilide of a cholera toxin-sensitive 40 kDa protein from pancreatic acinar cells.
In isolated pancreatic acinar plasma membranes a 40 kDa protein was labeled with the photoreactive GTP-analogue [alpha 32P] GTP-gamma-azidoanilide. Increased incorporation of the photolabel into the 40 kDa protein was obtained in the presence of increasing concentrations of cholecystokinin-octapeptide (10(-8) - 10(-5) M) but not with carbachol. Adenylyl cyclase activating hormones such as vasoactive intestinal polypeptide and secretin had no effect. Pretreatment of plasma membranes with cholera toxin reduced incorporation of GTP-gamma-azidoanilide into the 40 kDa protein by about 30%. This reduction was reversed if ADP-ribosylation by cholera toxin was performed in the presence of cholecystokinin, whereas carbachol had no effect. The data indicate that a cholera toxin-sensitive 40 kDa GTP-binding protein is involved in functionally coupling cholecystokinin- but not muscarinic acetylcholine-receptors to phospholipase C.
Max-Planck-Institut für Biophysik, Frankfurt, FRG.
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Schäfer
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Christian
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Schulz
D000262:Adenylyl Cyclases / Q000378:metabolism; D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D001386:Azides / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002772:Cholera Toxin / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D010179:Pancreas / Q000032:analysis* / Q000187:drug effects; D010777:Photochemistry; D051381:Rats; D012633:Secretin / Q000494:pharmacology; D012844:Sincalide / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D000345:Affinity Labels; D001386:Azides; D008565:Membrane Proteins; D012633:Secretin; D014660:Vasoactive Intestinal Peptide; C031907:GTP gamma-4-azidoanilide; D006160:Guanosine Triphosphate; D002217:Carbachol; D002772:Cholera Toxin; D000262:Adenylyl Cyclases; D012844:Sincalide