Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
A G protein-gated K channel is activated via beta 2-adrenergic receptors and G beta gamma subunits in Xenopus oocytes.
Lim NF
,
Dascal N
,
Labarca C
,
Davidson N
,
Lester HA
.
???displayArticle.abstract???
In many tissues, inwardly rectifying K channels are coupled to seven-helix receptors via the Gi/Go family of heterotrimeric G proteins. This activation proceeds at least partially via G beta gamma subunits. These experiments test the hypothesis that G beta gamma subunits activate the channel even if released from other classes of heterotrimeric G proteins. The G protein-gated K channel from rat atrium, KGA/GIRK1, was expressed in Xenopus oocytes with various receptors and G proteins. The beta 2-adrenergic receptor (beta 2AR), a Gs-linked receptor, activated large KGA currents when the alpha subunit, G alpha s, was also overexpressed. Although G alpha s augmented the coupling between beta 2AR and KGA, G alpha s also inhibited the basal, agonist-independent activity of KGA. KGA currents stimulated via beta 2AR activated, deactivated, and desensitized more slowly than currents stimulated via Gi/Go-linked receptors. There was partial occlusion between currents stimulated via beta 2AR and the m2 muscarinic receptor (a Gi/Go-linked receptor), indicating some convergence in the mechanism of activation by these two receptors. Although stimulation of beta 2AR also activates adenylyl cyclase and protein kinase A, activation of KGA via beta 2AR is not mediated by this second messenger pathway, because direct elevation of intracellular cAMP levels had no effect on KGA currents. Experiments with other coexpressed G protein alpha and beta gamma subunits showed that (a) a constitutively active G alpha s mutant did not suppress basal KGA currents and was only partially as effective as wild type G alpha s in coupling beta 2AR to KGA, and (b) beta gamma subunits increased basal KGA currents. These results reinforce present concepts that beta gamma subunits activate KGA, and also suggest that beta gamma subunits may provide a link between KGA and receptors not previously known to couple to inward rectifiers.
Birnbaumer,
Receptor-to-effector signaling through G proteins: roles for beta gamma dimers as well as alpha subunits.
1992, Pubmed
Birnbaumer,
Receptor-to-effector signaling through G proteins: roles for beta gamma dimers as well as alpha subunits.
1992,
Pubmed
Breitwieser,
Uncoupling of cardiac muscarinic and beta-adrenergic receptors from ion channels by a guanine nucleotide analogue.
,
Pubmed
Brown,
G-proteins and potassium currents in neurons.
1990,
Pubmed
Chen,
Differential regulation by cAMP-dependent protein kinase and protein kinase C of the mu opioid receptor coupling to a G protein-activated K+ channel.
1994,
Pubmed
,
Xenbase
Clapham,
New roles for G-protein beta gamma-dimers in transmembrane signalling.
1993,
Pubmed
Clapham,
Direct G protein activation of ion channels?
1994,
Pubmed
Codina,
The alpha subunit of the GTP binding protein Gk opens atrial potassium channels.
1987,
Pubmed
Dascal,
Expression of an atrial G-protein-activated potassium channel in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
Dascal,
Atrial G protein-activated K+ channel: expression cloning and molecular properties.
1993,
Pubmed
,
Xenbase
Fong,
Repetitive segmental structure of the transducin beta subunit: homology with the CDC4 gene and identification of related mRNAs.
1986,
Pubmed
Gautam,
A G protein gamma subunit shares homology with ras proteins.
1989,
Pubmed
Graziano,
Synthesis in Escherichia coli of GTPase-deficient mutants of Gs alpha.
1989,
Pubmed
Ho,
Cloning and expression of an inwardly rectifying ATP-regulated potassium channel.
1993,
Pubmed
,
Xenbase
Ito,
On the mechanism of basal and agonist-induced activation of the G protein-gated muscarinic K+ channel in atrial myocytes of guinea pig heart.
1991,
Pubmed
Ito,
On the mechanism of G protein beta gamma subunit activation of the muscarinic K+ channel in guinea pig atrial cell membrane. Comparison with the ATP-sensitive K+ channel.
1992,
Pubmed
Jones,
Golf: an olfactory neuron specific-G protein involved in odorant signal transduction.
1989,
Pubmed
Karschin,
Heterologously expressed serotonin 1A receptors couple to muscarinic K+ channels in heart.
1991,
Pubmed
Kim,
Beta-adrenergic regulation of the muscarinic-gated K+ channel via cyclic AMP-dependent protein kinase in atrial cells.
1990,
Pubmed
Kobilka,
Functional activity and regulation of human beta 2-adrenergic receptors expressed in Xenopus oocytes.
1987,
Pubmed
,
Xenbase
Kubo,
Primary structure and functional expression of a mouse inward rectifier potassium channel.
1993,
Pubmed
,
Xenbase
Kubo,
Primary structure and functional expression of a rat G-protein-coupled muscarinic potassium channel.
1993,
Pubmed
,
Xenbase
Kurachi,
On the mechanism of activation of muscarinic K+ channels by adenosine in isolated atrial cells: involvement of GTP-binding proteins.
1986,
Pubmed
Kurachi,
Activation of atrial muscarinic K+ channels by low concentrations of beta gamma subunits of rat brain G protein.
1989,
Pubmed
Kurachi,
G protein activation of cardiac muscarinic K+ channels.
1992,
Pubmed
Lechleiter,
Distinct sequence elements control the specificity of G protein activation by muscarinic acetylcholine receptor subtypes.
1990,
Pubmed
,
Xenbase
Logothetis,
The beta gamma subunits of GTP-binding proteins activate the muscarinic K+ channel in heart.
,
Pubmed
Logothetis,
Specificity of action of guanine nucleotide-binding regulatory protein subunits on the cardiac muscarinic K+ channel.
1988,
Pubmed
Mager,
Steady states, charge movements, and rates for a cloned GABA transporter expressed in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
Masters,
Mutations in the GTP-binding site of GS alpha alter stimulation of adenylyl cyclase.
1989,
Pubmed
McCarty,
Voltage-dependent block of the cystic fibrosis transmembrane conductance regulator Cl- channel by two closely related arylaminobenzoates.
1993,
Pubmed
,
Xenbase
Miyake,
Single potassium channels opened by opioids in rat locus ceruleus neurons.
1989,
Pubmed
Nargeot,
Time course of the increase in the myocardial slow inward current after a photochemically generated concentration jump of intracellular cAMP.
1983,
Pubmed
North,
Twelfth Gaddum memorial lecture. Drug receptors and the inhibition of nerve cells.
1989,
Pubmed
Okabe,
The nature and origin of spontaneous noise in G protein-gated ion channels.
1991,
Pubmed
Oñate,
Xenopus laevis oocyte G alpha subunits mRNAs. Detection and quantitation during oogenesis and early embryogenesis by competitive reverse PCR.
1992,
Pubmed
,
Xenbase
Pfaffinger,
GTP-binding proteins couple cardiac muscarinic receptors to a K channel.
,
Pubmed
Reuveny,
Activation of the cloned muscarinic potassium channel by G protein beta gamma subunits.
1994,
Pubmed
,
Xenbase
Riordan,
The cystic fibrosis transmembrane conductance regulator.
1993,
Pubmed
Simon,
Diversity of G proteins in signal transduction.
1991,
Pubmed
Soejima,
Mode of regulation of the ACh-sensitive K-channel by the muscarinic receptor in rabbit atrial cells.
1984,
Pubmed
Trautwein,
The effect of intracellular cyclic nucleotides and calcium on the action potential and acetylcholine response of isolated cardiac cells.
1982,
Pubmed
Trautwein,
Regulation of cardiac L-type calcium current by phosphorylation and G proteins.
1990,
Pubmed
Uezono,
Receptors that couple to 2 classes of G proteins increase cAMP and activate CFTR expressed in Xenopus oocytes.
1993,
Pubmed
,
Xenbase
VanDongen,
Newly identified brain potassium channels gated by the guanine nucleotide binding protein Go.
1988,
Pubmed
Wickman,
Recombinant G-protein beta gamma-subunits activate the muscarinic-gated atrial potassium channel.
1994,
Pubmed
Yamashita,
Pertussis toxin inhibits somatostatin-induced K+ conductance in human pituitary tumor cells.
1987,
Pubmed
Yatani,
Direct activation of mammalian atrial muscarinic potassium channels by GTP regulatory protein Gk.
1987,
Pubmed
Yatani,
Reconstitution of somatostatin and muscarinic receptor mediated stimulation of K+ channels by isolated GK protein in clonal rat anterior pituitary cell membranes.
1987,
Pubmed
Yatani,
The G protein-gated atrial K+ channel is stimulated by three distinct Gi alpha-subunits.
1988,
Pubmed
