ADP ribosylation by cholera toxin identifies three G-proteins that are activated by the galanin receptor. Studies with RINm5F cell membranes

Gillison, S. L.; Sharp, Geoffrey W. G.

doi:10.2337/diabetes.43.1.24

Cited by 14 publications

(11 citation statements)

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“…Unlike the a-subunits of G s , under basal unstimulated conditions, G r and G o -proteins are very poor substrates for CTX. However, during interaction.with activated receptors, G ; and G o do become substrates for CTX (20,22,23). This is due to a conformational change in the G-protein during the receptor interaction and GDP/GTP exchange and most likely occurs during the nucleotide-free state, i.e., after GDP has been lost and before GTP binding during the receptor interaction.…”

Section: Resultsmentioning

confidence: 98%

“…This is due to a conformational change in the G-protein during the receptor interaction and GDP/GTP exchange and most likely occurs during the nucleotide-free state, i.e., after GDP has been lost and before GTP binding during the receptor interaction. Consequently, CTX labeling can and has been used to identify those G-proteins that interact with a particular receptor (20). Furthermore, the extent of labeling may reflect the amount of time spent in the favorable CTX-substrate conformation in association with the receptor and the number of receptor-G-protein interactions taking place.…”

Section: Resultsmentioning

confidence: 99%

“…The best known substrate for ADP ribosylation by CTX is the a-subunit of G s . However, during receptor-G-protein activation, the a-subunits of G { and G o are also substrates for CTX, so "labeling" by CTX and [ 32 P]NAD can be used to identify the specific G f and G o -proteins that interact with a particular receptor (20,22,23). The results of these experiments are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…CTX-catalyzed ADP ribosylation and SDS-PAGE. The method was similar to that described previously (20). CTX holoenzyme was activated by 5 mmol/1 DTT at 30°C for 30 min in 20 mmol/1 Tris, pH 7.4.…”

Section: Methodsmentioning

confidence: 99%

“…Consequently, as a step toward answering these questions, we have compared the effects of two activated receptors, those for norepinephrine and galanin, on the rates of receptor-G-protein interaction (by GTP7S binding) and the rates of activation and turnover of G-proteins (by measurement of GTPase activity) in the same 3-cell membranes. RINm5F cell membranes were used because of the already extensive characterization of the effects of galanin and other inhibitors (7)(8)(9)(10)(11)(12)(17)(18)(19)(20)(21) in this cell type. We also compared the ability of norepinephrine and galanin to facilitate ADP ribosylation of the a-subunits of G v and G o by cholera toxin (CTX).…”

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confidence: 99%

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The α2-Adrenergic Receptor Is More Effective Than the Galanin Receptor in Activating G-Proteins in RINm5F β-cell Membranes

Gillison

Straub²,

Sharp³

1997

Diabetes

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Activated receptors for galanin and norepinephrine, and for several other agonists, inhibit insulin release from pancreatic beta-cells via pertussis toxin-sensitive Gi- and Go-proteins and by acting on at least four cellular mechanisms. These mechanisms include repolarization via activation of the ATP-sensitive potassium (K ATP) channel, inhibition of adenylyl cyclase, and inhibition by unknown mechanism at a "distal" site. For norepinephrine and galanin there is also inhibition of the L-type Ca2+ channel. Consequently, during simultaneous activation by multiple agonists, the effectiveness with which a receptor interacts with the G-proteins will, to some extent, determine the responses. This could have important consequences for the beta-cell. Therefore, the G-protein interactions of two activated receptors, those for norepinephrine and galanin, were compared in the same beta-cell membranes. Measurements were made of the rates of receptor-G-protein interaction (by GTPgammaS binding) and of the rates of turnover of G-proteins (by GTPase activity). A comparison was also made of the ability of norepinephrine and galanin to facilitate ADP ribosylation of the alpha-subunits of Gi and Go by cholera toxin (CTX). Such CTX-induced ADP ribosylation of Gi and Go occurs during G-protein interaction with an activated receptor. By measurement of the number of receptors in the membrane preparation used, the relative effectiveness of the two receptors was assessed. The alpha2-adrenergic receptor was found to be markedly more effective than the galanin receptor in activating G-proteins.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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The α2-Adrenergic Receptor Is More Effective Than the Galanin Receptor in Activating G-Proteins in RINm5F β-cell Membranes

Gillison

Straub²,

Sharp³

1997

Diabetes

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Electrophysiology of the β Cell and Mechanisms of Inhibition of Insulin Release

Dunne

Ämmälä

Straub

et al. 2001

Comprehensive Physiology

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The sections in this article are: Ion Channels in Insulin‐Secreting Cells Adenosine Triphosphate–Sensitive Potassium Channels Extracellular Control of Adenosine Triphosphate‐Sensitive Potassium Channel Function Therapeutic Manipulation by Modulators of Adenosine Triphosphate‐Sensitive Potassium Channels Architecture of the β‐cell Adenosine Triphosphate‐Sensitive Potassium Channel Calcium‐Selective Ion Channels Voltage‐Gated Sodium Channels Voltage‐Gated Potassium Channels Voltage‐Independent Potassium Channels Nonselective Cation Channels Anion‐Selective Channels Ionic Defects of β‐Cell Function Persistent Hyperinsulinemic Hypoglycemia of Infancy Altered Ionic Control of β Cells and Hypersecretion of Insulin Correlation of Gene Defects in the Adenosine Triphosphate‐Sensitive Potassium Channel with Persistent Hyperinsulinemic Hypoglycemia of Infancy Clinical Therapy for Persistent Hyperinsulinemic Hypoglycemia of Infancy Implications for Diabetes Mellitus Stimulus‐Secretion Coupling Mechanisms Other Than Depolarization Novel Methods for the Measurement of Insulin Secretion Capacitance Amperometry and Voltametry Calcium and Exocytosis Cyclic Adenosine Monophosphate and Exocytosis Effects of Phospholipases and Protein Kinases C and A Sulfonylureas and Exocytosis G Proteins and Exocytosis Other Modulators of Exocytosis Modeling Calcium‐, Cyclic, and Adenosine Monophosphate–, and Guanosine Triphosphate–Dependent Exocytosis Molecular Mechanisms of Exocytosis in the β Cell Receptor‐Mediated Inhibition of Insulin Release: Early and Late Effects Involvement of G Proteins Receptor–G Protein Interactions Inhibitory Mechanisms Adenosine Triphosphate–Sensitive Potassium Channel Activation and Membrane Repolarization Calcium Channel Inhibition Inhibition of Adenylate Cyclase Inhibition at a Distal Site G Protein–Target Interactions Adenosine Triphosphate–Sensitive Potassium Channel L‐Type Calcium Channels Adenylate Cyclase Distal Inhibitory Site Other Possible Mechanisms Inhibition of Glucose Metabolism Inhibition of Fatty Acid Metabolism Stimulation of Calcium–Adenosine Triphosphatase Activity Cyclic Guanosine Monophosphate Cytoskeleton Summary of Inhibitory Mechanisms

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