title: Voltage affects the dissociation rate constant of the m2 muscarinic receptor.
abstract: G-protein coupled receptors (GPCRs) comprise the largest protein family and mediate the vast majority of signal transduction processes in the body. Until recently GPCRs were not considered to be voltage dependent. Newly it was shown for several GPCRs that the first step in GPCR activation, the binding of agonist to the receptor, is voltage sensitive: Voltage shifts the receptor between two states that differ in their binding affinity. Here we show that this shift involves the rate constant of dissociation. We used the m2 muscarinic receptor (m2R) a prototypical GPCR and measured directly the dissociation of [(3)H]ACh from m2R expressed Xenopus oocytes. We show, for the first time, that the voltage dependent change in affinity is implemented by voltage shifting the receptor between two states that differ in their rate constant of dissociation. Furthermore, we provide evidence that suggest that the above shift is achieved by voltage regulating the coupling of the GPCR to its G protein.
authors.affiliation: Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel.
authors.forename: Yair
authors.initials: Y
authors.lastname: Ben Chaim
authors.forename: Shimrit
authors.initials: S
authors.lastname: Bochnik
authors.forename: Itzchak
authors.initials: I
authors.lastname: Parnas
authors.forename: Hanna
authors.initials: H
authors.lastname: Parnas
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D007700:Kinetics; D008564:Membrane Potentials; D011485:Protein Binding; D043585:Receptor, Muscarinic M2 / Q000378:metabolism*; D014981:Xenopus
chemical_list: D043585:Receptor, Muscarinic M2; D000109:Acetylcholine
references.citation: Mol Pharmacol. 1990 Oct;38(4):517-23
references.pmid: 2172767
references.citation: J Gen Physiol. 1988 Apr;91(4):469-93
references.pmid: 2455765
references.citation: Cell Signal. 1997 Dec;9(8):551-73
references.pmid: 9429760
references.citation: Neuropharmacology. 2011 Oct-Nov;61(5-6):937-49
references.pmid: 21752340
references.citation: J Biol Chem. 2005 Jan 14;280(2):1490-8
references.pmid: 15528188
references.citation: Annu Rev Biochem. 1987;56:615-49
references.pmid: 3113327
references.citation: CRC Crit Rev Biochem. 1987;22(4):317-87
references.pmid: 2449311
references.citation: Neuron. 2002 Jan 3;33(1):87-99
references.pmid: 11779482
references.citation: Proc Natl Acad Sci U S A. 2013 Jan 22;110(4):1536-41
references.pmid: 23297214
references.citation: J Biol Chem. 2003 Jun 20;278(25):22482-91
references.pmid: 12684524
references.citation: J Biol Chem. 1993 May 5;268(13):9824-38
references.pmid: 8387506
references.citation: Biochem Biophys Res Commun. 2008 Dec 26;377(4):1216-21
references.pmid: 18983826
references.citation: Biochem Biophys Res Commun. 2008 Sep 26;374(3):496-501
references.pmid: 18652803
references.citation: J Physiol. 2011 Apr 1;589(Pt 7):1741-53
references.pmid: 21282291
references.citation: J Biol Chem. 1980 Aug 10;255(15):7108-17
references.pmid: 6248546
references.citation: J Biol Chem. 1999 Oct 8;274(41):29519-28
references.pmid: 10506217
references.citation: FASEB J. 1997 Apr;11(5):346-54
references.pmid: 9141501
references.citation: Synapse. 2008 Jun;62(6):476-80
references.pmid: 18361445
references.citation: J Biol Chem. 1998 Jan 9;273(2):669-72
references.pmid: 9422713
references.citation: J Biol Chem. 2001 Dec 14;276(50):47512-7
references.pmid: 11591725
references.citation: J Biol Chem. 1986 Sep 25;261(27):12498-505
references.pmid: 2427520
references.citation: Proc Natl Acad Sci U S A. 2012 Jan 3;109(1):285-90
references.pmid: 22184214
references.citation: J Physiol. 1997 Oct 15;504 ( Pt 2):251-8
references.pmid: 9365901
references.citation: Trends Pharmacol Sci. 2008 Aug;29(8):421-9
references.pmid: 18621424
references.citation: J Cell Biol. 2011 Jan 10;192(1):137-51
references.pmid: 21200029
references.citation: Sci STKE. 2003 Nov 25;2003(210):pe52
references.pmid: 14645810
references.citation: Endocr Rev. 2000 Feb;21(1):90-113
references.pmid: 10696571
references.citation: Trends Neurosci. 2007 Feb;30(2):54-61
references.pmid: 17169441
references.citation: Am J Physiol. 1995 Oct;269(4 Pt 1):C821-30
references.pmid: 7485449
references.citation: J Neurophysiol. 2005 Jun;93(6):3257-69
references.pmid: 15703226
references.citation: J Biol Chem. 2006 Aug 25;281(34):24204-15
references.pmid: 16760467
references.citation: Trends Neurosci. 2000 Feb;23(2):60-8
references.pmid: 10652546
references.citation: Nature. 2012 Jan 25;482(7386):547-51
references.pmid: 22278061
references.citation: Proc Natl Acad Sci U S A. 2003 May 13;100(10):6239-44
references.pmid: 12719528
references.citation: Nature. 2006 Nov 2;444(7115):106-9
references.pmid: 17065983
references.citation: J Physiol. 1989 Dec;419:665-87
references.pmid: 2482887