Evidence that thyrotropin-releasing hormone-induced increases in GTPase activity and phosphoinositide metabolism in GH3 cells are mediated by a guanine nucleotide-binding protein other than Gs or Gi.
Thyrotropin-releasing hormone (TRH), vasoactive intestinal polypeptide (VIP) and acetylcholine stimulated high affinity GTPase activity in GH3 cell membrane preparations. The effects of acetylcholine and VIP were blocked by pretreatment of cultured cells with pertussis toxin and cholera toxin respectively. Such pretreatment, which causes covalent modification of the guanine nucleotide-binding proteins (G-proteins) of adenylate cyclase, did not, however, block the effects of TRH on GTPase activity or phosphoinositide breakdown. These data suggest that TRH receptors interact with a G-protein discrete from those associated with regulation of adenylate cyclase activity.
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D037361:Adenylate Cyclase Toxin; D000818:Animals; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010903:Pituitary Gland, Anterior; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D013973:Thyrotropin-Releasing Hormone; D002772:Cholera Toxin; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins