Wheat germ agglutinin inhibits basal- and stimulated-adenylate cyclase activity as well as the binding of [3H] caerulein to rat pancreatic plasma membranes.
Wheat germ agglutinin, but not concanavalin A or soybean lectin, inhibited the basal-and stimulated-adenylate cyclase activity which was present in a plasma membrane preparation from the rat pancreas. The inhibition by wheat germ agglutinin was rapid and sustained. It was of the non-competitive type and never exceeded 20% for Gpp (NH) p- and NaF-stimulated adenylate cyclase activity. The inhibition of secretin-stimulated activity was also non-competitive but more pronounced (57% inhibition at a wheat germ agglutinin concentration of 20 microgram/ml). For the C-terminal octapeptide of cholecystokinin-pancreozymin (OC-PZ)-stimulated cyclase, the inhibition amounted to 68% and was of a mixed type (both competitive and non-competitive). This last observation might be explained by the competitive inhibition exerted by wheat germ agglutinin on the binding of peptides of the OC-PZ family to their membrane specific receptors. The various inhibitory effects of wheat germ agglutinin were completely suppressed by incubating the membranes in the presence of ovomucoid, a N-acetyl-D-glucosamine rich glycoprotein. The possible functional implication of these results is discussed.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002108:Ceruletide / Q000378:metabolism*; D002766:Cholecystokinin / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D037102:Lectins / Q000494:pharmacology*; D010059:Ovomucin / Q000494:pharmacology; D010179:Pancreas / Q000378:metabolism*; D037121:Plant Lectins; D011485:Protein Binding; D051381:Rats; D012633:Secretin / Q000494:pharmacology; D013025:Glycine max; D014908:Triticum
D037102:Lectins; D037121:Plant Lectins; D003208:Concanavalin A; D012633:Secretin; D006165:Guanylyl Imidodiphosphate; D010059:Ovomucin; D006160:Guanosine Triphosphate; D002108:Ceruletide; D002766:Cholecystokinin; D000262:Adenylyl Cyclases