Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2000 May 9;97(10):5651-6.
doi: 10.1073/pnas.080572297.

The role of members of the pertussis toxin-sensitive family of G proteins in coupling receptors to the activation of the G protein-gated inwardly rectifying potassium channel

J L Leaney  1 , A Tinker
Affiliations

The role of members of the pertussis toxin-sensitive family of G proteins in coupling receptors to the activation of the G protein-gated inwardly rectifying potassium channel

J L Leaney et al. Proc Natl Acad Sci U S A. .

Abstract

Inwardly rectifying potassium (K(+)) channels gated by G proteins (Kir3.x family) are widely distributed in neuronal, atrial, and endocrine tissues and play key roles in generating late inhibitory postsynaptic potentials, slowing the heart rate and modulating hormone release. They are directly activated by G(betagamma) subunits released from G protein heterotrimers of the G(i/o) family upon appropriate receptor stimulation. Here we examine the role of isoforms of pertussis toxin (PTx)-sensitive G protein alpha subunits (G(ialpha1-3) and G(oalphaA)) in mediating coupling between various receptor systems (A(1), alpha(2A), D(2S), M(4), GABA(B)1a+2, and GABA(B)1b+2) and the cloned counterpart of the neuronal channel (Kir3.1+3.2A). The expression of mutant PTx-resistant G(i/oalpha) subunits in PTx-treated HEK293 cells stably expressing Kir3.1+3.2A allows us to selectively investigate that coupling. We find that, for those receptors (A(1), alpha(2A)) known to interact with all isoforms, G(ialpha1-3) and G(oalphaA) can all support a significant degree of coupling to Kir3.1+3.2A. The M(4) receptor appears to preferentially couple to G(ialpha2) while another group of receptors (D(2S), GABA(B)1a+2, GABA(B)1b+2) activates the channel predominantly through G(betagamma) liberated from G(oA) heterotrimers. Interestingly, we have also found a distinct difference in G protein coupling between the two splice variants of GABA(B)1. Our data reveal selective pathways of receptor activation through different G(i/oalpha) isoforms for stimulation of the G protein-gated inwardly rectifying K(+) channel.

PubMed Disclaimer

Figures

Figure 1
Figure 1
The A1 adenosine receptor couples to Kir3.1+3.2A channels via Giα1–3 and GoαA. (A) This illustrates the experimental protocol used. The HKIR3.1/3.2/A1 monoclonal cell line stably expressing Kir3.1+3.2A channels together with the A1 receptor was transiently transfected with mutant PTx-insensitive Gi/oα subunits, and then cells were treated with PTx 1 day before electrophysiological recording. (B) These are examples of traces showing the effects of stimulating A1 receptors in the HKIR3.1/3.2/A1 cell line in PTx-treated cells (top traces) and when each of the mutated Gi/oα variants was co-expressed. Currents were elicited by holding cells at 0 mV and stepping to potentials between −100 and +50 mV in 10-mV increments for 100 ms. Traces indicate current responses before (Basal), during (+ NECA), and after (Wash) receptor stimulation.
Figure 2
Figure 2
The Gi/oα subunits have similar affinities in mediating signaling between A1 receptors and Kir3.1+3.2A. (A) Superimposed dose-response curves for NECA-induced activation of Kir3.1+3.2A channels in control, non-PTx treated cells (solid line) and in PTx-treated cells in which the mutant Gi/oα subunits (dashed lines), Giα1C351G, Giα2C352G, Giα3C351G, and GoαAC351G, have been co-expressed. (B) Bar chart summarizing the data obtained with the HKIR3.1/3.2/A1 cell line and expression of each of the Gi/o variants. Open bars represent basal currents, and solid bars represent current in response to receptor stimulation. Numbers in parentheses refer to the number of cells recorded from for each experiment. Current density was measured at −100 mV.
Figure 3
Figure 3
The α2A adrenergic receptor, D2S dopaminergic receptor, and M4 muscarinic receptor exhibit different coupling profiles to Gi/oα subunits. Summary of data obtained from studying coupling between the α2A adrenergic receptor (A), the D2S dopaminergic receptor (B) and the M4 muscarinic receptor (C), and Kir3.1+3.2A channels via the Giα1, Giα2, Giα3, and GoαA C∏ G mutants. Open bars represent basal currents, and solid bars represent current in response to receptor stimulation. Numbers in parentheses refer to the number of cells recorded from for each experiment. Current density was measured at −100 mV.
Figure 4
Figure 4
The two forms of the GABAB receptor activate Kir3.1+3.2A channels through different Gi/oα subunits. (A) Stimulation of both the GABAB1a+2 and the GABAB1b+2 receptor (100 μM baclofen) led to robust activation of the Kir3.1+3.2A channels. Currents were elicited as described in Fig. 1B. (B) Summary of data obtained from expression of the GABAB1a, -1b, and -2 subunits alone, and when expressed as the dimeric receptors GABAB1a+2 and GABAB1b+2. (B and D) Bar charts summarizing the data obtained with the GABAB1a+2 receptor (C) and the GABAB1b+2 receptor (D) when the mutant Gi/oα mutants were co-expressed in PTx-treated cells. Open bars represent basal currents, and solid bars represent current in response to receptor stimulation. Numbers in parentheses refer to the number of cells recorded from for each experiment. Current density was measured at −100 mV.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Dascal N, Schreibmayer W, Lim N F, Wang W, Chavkin C, DiMagno L, Labarca C, Kieffer B L, Gaveriaux-Ruff C, Trollinger D, et al. Proc Natl Acad Sci USA. 1993;90:10235–10239. - PMC - PubMed
    1. Kubo Y, Reuveny E, Slesinger P A, Jan Y N, Jan L Y. Nature (London) 1993;364:802–806. - PubMed
    1. Lesage F, Duprat F, Fink M, Guillemare E, Coppola T, Lazdunski M, Hugnot J-P. FEBS Lett. 1994;353:37–42. - PubMed
    1. Krapivinsky G, Gordon E A, Wickman K, Velimirovic B, Krapivinsky L, Clapham D E. Nature (London) 1995;374:135–141. - PubMed
    1. Hedin K E, Lim N F, Clapham D E. Neuron. 1996;16:423–429. - PubMed

Publication types

MeSH terms

LinkOut - more resources