Cholera toxin blocks glucagon-mediated inhibition of the liver plasma membrane (Ca2+-Mg2+)-ATPase

• Published in: The Journal of biological chemistry Vol. 262; no. 7; pp. 3114 - 3117
• Main Authors: Lotersztajn, S., Pavoine, C., Mallat, A., Stengel, D., Insel, P.A., Pecker, F.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05-03-1987; American Society for Biochemistry and Molecular Biology
• Subjects: Adenylate Cyclase Toxin; Adenylyl Cyclases - metabolism; Animals; Biological and medical sciences; Ca(2+) Mg(2+)-ATPase - antagonists & inhibitors; Calcium-Transporting ATPases - antagonists & inhibitors; Cell Membrane - enzymology; Cell physiology; Cholera Toxin - pharmacology; Female; Fundamental and applied biological sciences. Psychology; Glucagon - pharmacology; GTP-Binding Proteins - physiology; Liver - enzymology; Membrane and intracellular transports; Molecular and cellular biology; Pertussis Toxin; Rats; Rats, Inbred Strains; Virulence Factors, Bordetella - pharmacology; Glucagon; Rat; Liver; Vibrio cholerae; Rodentia; Ca,Mg-ATPase; Guanine nucleotide; Ion transport; Binding protein; Toxin; Vertebrata; Regulation(control); Mammalia; Hepatocyte; Animal; Plasma membrane; Bacteria; Vibrionaceae; Inhibition
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)61476-0

We have previously shown that liver plasma membrane (Ca2+-Mg2+)-ATPase activity is inhibited by glucagon. To investigate the possible involvement of a GTP-binding (G) protein in this regulation, we have examined the effects of pertussis toxin and cholera toxin on inhibition of (Ca2+-Mg2+)-ATPase by glucagon. Treatment of liver plasma membranes with pertussis toxin did not affect the sensitivity of (Ca2+-Mg2+)-ATPase to the hormone. In contrast, treatment of plasma membranes or prior injection of animals with cholera toxin prevented inhibition of the (Ca2+-Mg2+)-ATPase by glucagon. Even though adenylate cyclase activity was increased by cholera toxin treatment, addition of cyclic AMP did not mimic the effect of cholera toxin in blocking glucagon-mediated inhibition of (Ca2+-Mg2+)-ATPase activity. These data suggest that a cholera toxin-sensitive protein, perhaps Gs or a Gs-like protein, is involved in the regulation of liver (Ca2+-Mg2+)-ATPase activity. The results emphasize the possible role of Gs-like proteins in regulation of enzymes other than adenylate cyclase and suggest that the study of (Ca2+-Mg2+)-ATPase may provide a useful enzymatic system to examine such regulation.