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Acetylcholine and cholecystokinin receptors functionally couple by different G‐proteins to phospholipase C in pancreatic acinar cells
Author(s) -
Schnefel S.,
Banfic H.,
Eckhardt L.,
Schultz G.,
Schulz I.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80655-0
Subject(s) - cholera toxin , adenylyl cyclase , pertussis toxin , g protein , muscarinic acetylcholine receptor , phospholipase c , phospholipase , chemistry , cholecystokinin , gtp' , receptor , carbachol , medicine , cholecystokinin receptor , endocrinology , biology , biochemistry , enzyme
We have studied the involvement of GTP‐binding proteins in the stimulation of phospholipase C from rat pancreatic acinar cells. Pretreatment of permeabilized cells with activated cholera toxin inhibited both cholecystokinin‐octapeptide (CCK‐OP) and GTPγS but not carbachol (CCh)‐induced production of inositol trisphosphate. Pertussis toxin had no effect. Neither vasoactive intestinal polypeptide, a stimulator of adenylyl cyclase, nor the cAMP‐analogue, 8‐bromo cAMP, mimicked the inhibitory effect of cholera toxin on agonist‐induced phospholipase C activation. This indicates that inhibition by cholera toxin could not be attributed to a direct interaction of cholera toxin activated G s with phospholipase C or to an elevation of cAMP. In isolated rat pancreatic plasma membranes cholera toxin ADP‐ribosylated a 40 kDa protein, which was inhibited by CCK‐OP but not by CCh. We conclude from these data that both CCK‐ and muscarinic acetylcholine receptors functionally couple to phospholipase C by two different GTP‐binding proteins.