scholarly journals Activation of the inhibitory GTP-binding protein of adenylate cyclase, Gi, by beta-adrenergic receptors in reconstituted phospholipid vesicles.

1984 ◽  
Vol 259 (15) ◽  
pp. 9351-9354 ◽  
Author(s):  
T Asano ◽  
T Katada ◽  
A G Gilman ◽  
E M Ross
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Binding Protein ◽  
Phospholipid Vesicles ◽  
Beta Adrenergic Receptors ◽  
Gtp Binding Protein ◽  
Beta Adrenergic ◽  
Gtp Binding

scholarly journals Rhodopsin-enhanced GTPase activity of the inhibitory GTP-binding protein of adenylate cyclase.

1984 ◽  
Vol 259 (12) ◽  
pp. 7378-7381 ◽  
Author(s):  
Y Kanaho ◽  
S C Tsai ◽  
R Adamik ◽  
E L Hewlett ◽  
J Moss ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Binding Protein ◽  
Gtpase Activity ◽  
Gtp Binding Protein ◽  
Gtp Binding

scholarly journals Mechanism of acetylcholine-induced inhibition of Ca current in bullfrog atrial myocytes.

1990 ◽  
Vol 96 (4) ◽  
pp. 865-885 ◽  
Author(s):  
T Nakajima ◽  
S Wu ◽  
H Irisawa ◽  
W Giles
Keyword(s):  
Adenylate Cyclase ◽  
Binding Protein ◽  
Cell Voltage ◽  
Inhibitory Effect ◽  
Atrial Myocytes ◽  
Ca Current ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Subsequent Application ◽  
Gamma S

The mechanism of the anti-beta-adrenergic action of acetylcholine (ACh) on Ca current, ICa, was examined using the tight-seal, whole-cell voltage clamp technique in single atrial myocytes from the bullfrog. Both isoproterenol (ISO) and forskolin increased ICa dose dependently. After ICa had been enhanced maximally by ISO (10(-6) M), subsequent application of forskolin (50 microM) did not further increase ICa, suggesting that ISO and forskolin increase ICa via a common biochemical pathway, possibly by stimulation of adenylate cyclase. ACh (10(-5) M) completely inhibited the effect of low doses of forskolin (2 x 10(-6) M), as well as ISO, but it failed to block the effects of high doses of forskolin (greater than 5 x 10(-5) M). Intracellular application of cyclic AMP (cAMP) also increased ICa. ACh (10(-5) M) failed to inhibit this cAMP effect, indicating that the inhibitory action of ACh occurs at a site proximal to the production of cAMP. ACh (10(-5) M) also activated an inwardly rectifying K+ current IK(ACh). Intracellular application of a nonhydrolyzable GTP analogue, GTP gamma S (5 X 10(-4) M), activated IK(ACh) within several minutes; subsequent application of ACh (10(-5) M) did not increase IK(ACh) further. These results demonstrate that a GTP-binding protein coupled to these K+ channels can be activated maximally by GTP gamma S even in the absence of ACh. Intracellular application of GTP gamma S also strongly inhibited the effect of ISO on ICa in the absence of ACh. Pertussis toxin (IAP) completely prevented both the inhibitory effect of ACh on ICa and the ACh-induced activation of IK(ACh). GTP gamma S (50 microM-1 mM) alone did not increase ICa significantly; however, when ISO was applied first, GTP gamma S (5 x 10(-4) M) gradually inhibited the ISO effect on ICa. These results indicate that ACh antagonizes the effect of ISO on ICa via a GTP-binding protein (Gi and/or Go). This effect may be mediated through a direct inhibition by the alpha-subunit of Gi which is coupled to the adenylate cyclase.

scholarly journals Primary structure of bovine cerebellum GTP-binding protein G39 and its effect on the adenylate cyclase system

FEBS Letters ◽  
1987 ◽  
Vol 226 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Yu.A. Ovchinnikov ◽  
V.Z. Slepak ◽  
A.N. Pronin ◽  
A.B. Shlensky ◽  
N.B. Levina ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Primary Structure ◽  
Binding Protein ◽  
Adenylate Cyclase System ◽  
Gtp Binding Protein ◽  
Gtp Binding

scholarly journals Evidence for regulation of human platelet adenylate cyclase by phosphorylation. Inhibition by ATP and guanosine 5′-[β-thio]diphosphate occur by distinct mechanisms

1991 ◽  
Vol 276 (3) ◽  
pp. 621-630 ◽  
Author(s):  
I A Wadman ◽  
R W Farndale ◽  
B R Martin
Keyword(s):  
Creatine Kinase ◽  
Adenylate Cyclase ◽  
Human Platelet ◽  
Binding Protein ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Phosphoryl Transfer ◽  
Activation Process ◽  
Gtp Binding Protein ◽  
Gtp Binding

1. Incubation of human platelet membranes with guanosine 5′-[beta gamma-imido]triphosphate (p[NH]ppG) causes a time-dependent increase in the activation of adenylate cyclase due to Gs (the stimulatory GTP-binding protein). Forskolin enhances adenylate cyclase activity but does not interfere with the process of activation. The activation follows first-order kinetics in both the presence and the absence of the assay components. 2. ATP in the presence or the absence of an ATP-regenerating system of phosphocreatine and creatine kinase inhibits activation. 3. Hydrolysis of ATP to ADP does not lead to receptor-mediated inhibition of adenylate cyclase acting via Gi (the inhibitory GTP-binding protein). The ADP analogue adenosine 5′-[beta-thio]diphosphate (ADP[S]) does not inhibit the activation process. 4. Phosphocreatine alone inhibits adenylate cyclase activation at concentrations above 1 mM. 5. Inhibition by phosphocreatine is not due to the chelation of free Mg2+ ions. 6. Inhibition by ATP and the other assay components occurs throughout the activation process, decreasing both the rate of activation and the maximum activity obtained. 7. Maximal activation of adenylate cyclase after prolonged incubation with p[NH]ppG slowly reverses in the presence of the assay components. 8. A 10-fold excess of the GDP analogue guanosine 5′-[beta-thio]diphosphate (GDP[S]) over p[NH]ppG inhibits the activation process completely, at all stages of the time course. 9. Preincubations in the presence and absence of ATP, cyclic AMP, phosphocreatine and creatine kinase show equal sensitivity to increasing GDP[S] concentration. These data show that the inhibition observed in the presence of ATP is not due to endogenous or contaminating guanine nucleotides, and suggest that phosphoryl transfer may regulate adenylate cyclase activity.

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