Possible Interaction: Glucagon and Trypsin

“Recently, with a new method that uses tryptic digestion, the G protein coupled … but not of Gs alpha-S. By contrast, the present study showed that glucagon … trypsin in a concentration-dependent manner, indicating that GRs are coupled to … another Gs, Gs-S, in partially hepatectomized male rat livers.”

“Reduced or no … effect of glucagon was observed: (a) after limited proteolysis of plasma membrane proteins by trypsin , (b) in the presence of 1 mM Mn2+, (c) in the absence of Na+, and (d) during the first 10 min of incubation if GuoPP[NH]P was the activating ligand.”

“The administration of glucagon was followed by a significant decrease (30.8%) in the volume of the duodenal contents and a more pronounced depression of the enzyme concentrations ( trypsin 59%, chymotrypsin 53.3%).”

“Treatment of the hepatocytes with trypsin markedly reduced the response to glucagon.”

“Further, trypic cleavage of the anglerfish glucagon requires higher concentrations of trypsin (molar ratio 1:25 enzyme to substrate) and longer incubation time.”

“The effect of glucagon was impaired by pretreatment of adipose cells with trypsin (0.2 mg/ml and 2.0 mg/ml) and N -ethylmaleimide (5 mmol/l).”

“As previously found for the processes of … cyclase, the process of inactivation of glucagon is blocked … heat, urea, trypsin , or phospholipase A. The specific activity of the glucagon-inactivation process increases to the same … cyclase activity in the membranes compared to a 1500 x g sediment of liver homogenate.”

“Pretreatment of adipose tissue with trypsin decreased by 44% the lipolytic response of isolated fat cells to glucagon , but it had no effect on their response to secretin and ACTH.”

“These results indicate that trypsin modifies rather selectively the effector systems for insulin and glucagon without affecting other metabolic systems of the cell, including the effector systems for epinephrine and adrenocorticotropic hormone.”