Biochemical characterization of three stimulatory GTP-binding proteins. The large and small forms of Gs and the olfactory-specific G-protein, Golf.
The biochemical properties of three stimulatory guanine nucleotide-binding protein (G-protein) alpha subunits, the large and small forms of Gs, Gs-l (52 kDa) and Gs-s (45 kDa), and the olfactory specific G-protein, Golf, have been compared. Complementary DNAs (cDNAs) encoding each alpha subunit were independently expressed in a mammalian cell line deficient in endogenous stimulatory G-proteins (S49 cyc-kin-). Gs-l and Gs-s respond similarly to activation by the beta-adrenergic agonist isoproterenol (EC50 = 80 and 60 nM, respectively) and the receptor-independent G-protein activators guanosine 5-O-3-(thio)triphosphate) (GTP gamma S) and AlF-4. The ability of Golf to interact with the beta-adrenergic receptor was also examined. Surprisingly, Golf interacts with beta-adrenergic receptors and is activated by isoproterenol (EC50 = 120 nM). All three G-proteins respond similarly to treatment with different alpha, beta, and gamma thiophosphoryl analogs of GTP. Specifically, (R)-GTP alpha S and GTP gamma S activate each G-protein, whereas (S)-GTP alpha S and (R)- or (S)-GTP beta S are inactive. In addition, similar to Gs alpha, Golf alpha is covalently modified and constitutively activated by cholera toxin. These studies demonstrate that all three stimulatory G-proteins are functionally and structurally similar, however, subtle differences between Golf and the two forms of Gs appear to modulate their interactions with receptors.
Jones
D T
DT
Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Masters
S B
SB
Bourne
H R
HR
Reed
R R
RR
D000262:Adenylyl Cyclases / Q000378:metabolism; D000535:Aluminum / Q000494:pharmacology; D017607:Aluminum Compounds; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002490:Central Nervous System / Q000502:physiology*; D002772:Cholera Toxin / Q000378:metabolism / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004789:Enzyme Activation; D005459:Fluorides; D005461:Fluorine / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008024:Ligands; D046911:Macromolecular Substances; D008970:Molecular Weight; D009833:Olfactory Pathways / Q000502:physiology*; D051381:Rats; D015398:Signal Transduction
D017607:Aluminum Compounds; D008024:Ligands; D046911:Macromolecular Substances; C050992:tetrafluoroaluminate; D005461:Fluorine; D006160:Guanosine Triphosphate; D004247:DNA; D002772:Cholera Toxin; D000535:Aluminum; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D005459:Fluorides