Studies on the mechanism of the decreased guanine nucleotide stimulatory effects on adenylate cyclase after adrenalectomy in rat adipocytes.
In adipocyte membranes from adrenalectomized rats: (i) the defect in the stimulatory effects of guanine nucleotides on adenylate cyclase is greater with GTP than with GppNHp and appears to concern the GS-C complex and not the HR-GS-C ternary complex; (ii) the GTP-ase activity is enhanced; (iii) maximal alpha S-C interaction (tested by the responses to forskolin, cholera toxin or NaF) is unaltered and (iv) the alpha S affinity for guanine nucleotides and the GDP/GppNHp exchange reaction are both unimpaired. These data suggest that the enhanced GTP-ase activity together with a decrease in the catalytic activity of the alpha S-GTP-C complex are the likely mechanisms whereby adrenalectomy causes a defect in the fat cell adenylate cyclase response to guanine nucleotides.
de Mazancourt
P
P
Department of Biochemistry, Faculty of Medicine Paris-Ouest, Centre Hospitalier de Poissy, France.
Giot
J
J
Giudicelli
Y
Y
D000262:Adenylyl Cyclases / Q000502:physiology*; D000273:Adipose Tissue / Q000166:cytology / Q000201:enzymology*; D000315:Adrenalectomy; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D006150:Guanine Nucleotides / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012969:Sodium Fluoride / Q000494:pharmacology
D006150:Guanine Nucleotides; D005576:Colforsin; D012969:Sodium Fluoride; D002772:Cholera Toxin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007545:Isoproterenol