G protein activation by serotonin type 4 receptor dimers: evidence that turning on two protomers is more efficient.
The discovery that class C G protein-coupled receptors (GPCRs) function as obligatory dimeric entities has generated major interest in GPCR oligomerization. Oligomerization now appears to be a common feature among all GPCR classes. However, the functional significance of this process remains unclear because, in vitro, some monomeric GPCRs, such as rhodopsin and β(2)-adrenergic receptors, activate G proteins. By using wild type and mutant serotonin type 4 receptors (5-HT(4)Rs) (including a 5-HT(4)-RASSL) expressed in COS-7 cells as models of class A GPCRs, we show that activation of one protomer in a dimer was sufficient to stimulate G proteins. However, coupling efficiency was 2 times higher when both protomers were activated. Expression of combinations of 5-HT(4), in which both protomers were able to bind to agonists but only one could couple to G proteins, suggested that upon agonist occupancy, protomers did not independently couple to G proteins but rather that only one G protein was activated. Coupling of a single heterotrimeric G(s) protein to a receptor dimer was further confirmed in vitro, using the purified recombinant WT RASSL 5-HT(4)R obligatory heterodimer. These results, together with previous findings, demonstrate that, differently from class C GPCR dimers, class A GPCR dimers have pleiotropic activation mechanisms.
Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS UMR5203, F-34094 Montpellier, France.
Lucie P
LP
Pellissier
Gaël
G
Barthet
Florence
F
Gaven
Elisabeth
E
Cassier
Eric
E
Trinquet
Jean-Philippe
JP
Pin
Philippe
P
Marin
Aline
A
Dumuis
Joël
J
Bockaert
Jean-Louis
JL
Banères
Sylvie
S
Claeysen
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D055503:Protein Multimerization / Q000502:physiology*; D044422:Receptors, Serotonin, 5-HT4 / Q000235:genetics / Q000378:metabolism*
D044422:Receptors, Serotonin, 5-HT4; D020962:Heterotrimeric GTP-Binding Proteins
EMBO J. 2005 Jun 1;24(11):1954-64
15889138
J Comp Neurol. 2004 Jul 5;474(4):589-602
15174075
J Physiol. 1979 Mar;288:613-34
112243
Curr Opin Cell Biol. 1997 Apr;9(2):134-42
9069253
J Biol Chem. 2010 Feb 26;285(9):6337-47
20026606
Nat Chem Biol. 2009 Sep;5(9):688-95
19648932
EMBO J. 1999 Apr 1;18(7):1723-9
10202136
Photochem Photobiol Sci. 2004 Jun;3(6):628-38
15170495
Annu Rev Pharmacol Toxicol. 2008;48:107-41
17848137
J Biol Chem. 2005 May 27;280(21):20253-60
15774473
Nat Struct Mol Biol. 2004 Aug;11(8):706-13
15235591
Mol Pharmacol. 2007 Aug;72(2):219-30
17430994
J Biol Chem. 2003 Jan 10;278(2):699-702
12441358
EMBO J. 2005 Feb 9;24(3):499-509
15660124
FEBS J. 2005 Jun;272(12):2947-55
15955055
EMBO J. 1997 Nov 17;16(22):6737-47
9362488
Proc Natl Acad Sci U S A. 2004 Sep 28;101(39):14258-63
15353592
Anal Biochem. 2004 Jun 15;329(2):253-62
15158484
Mol Pharmacol. 2006 May;69(5):1652-61
16467191
FEBS Lett. 2005 Jun 6;579(14):2973-80
15896782
Proc Natl Acad Sci U S A. 2001 Apr 24;98(9):4819-21
11320227
Trends Pharmacol Sci. 2005 Mar;26(3):131-7
15749158
Trends Neurosci. 2008 Feb;31(2):74-81
18199492
Science. 2010 Nov 19;330(6007):1066-71
20929726
Mol Biol Cell. 2007 Jun;18(6):1979-91
17377064
J Biol Chem. 2005 Jul 29;280(30):27924-34
15919661
J Biol Chem. 2003 Feb 14;278(7):4385-8
12496294
Nat Chem Biol. 2008 Feb;4(2):126-31
18193048
J Cell Sci. 2001 Apr;114(Pt 7):1265-71
11256993
J Biol Chem. 2006 Apr 28;281(17):11917-22
16495215
J Biol Chem. 2005 Jul 1;280(26):24380-5
15863499
EMBO J. 2006 Dec 13;25(24):5693-702
17139258
J Biol Chem. 2008 Feb 15;283(7):4387-94
18033822
EMBO J. 2008 Sep 3;27(17):2293-304
18668123
Biochemistry. 1997 Jun 17;36(24):7361-79
9200684
Curr Opin Pharmacol. 2010 Feb;10(1):53-8
19910252
Proc Natl Acad Sci U S A. 2008 Oct 14;105(41):16045-50
18836069
J Biol Chem. 2005 May 20;280(20):19768-76
15769745
PLoS One. 2007 Dec 19;2(12):e1317
18338032
Proc Natl Acad Sci U S A. 2005 Jun 21;102(25):9050-5
15932946
J Biol Chem. 2004 Apr 16;279(16):16091-100
14764600
Proc Natl Acad Sci U S A. 2007 Jul 17;104(29):12199-204
17620610
J Biol Chem. 2005 Dec 2;280(48):40144-51
16195233
Nat Chem Biol. 2010 Aug;6(8):587-94
20622858
Mol Pharmacol. 2009 Apr;75(4):982-90
19168624
Biochim Biophys Acta. 2007 Apr;1768(4):794-807
17188232
J Biol Chem. 2009 Sep 25;284(39):26732-41
19542234
Anal Biochem. 2001 Apr 1;291(1):109-17
11262163
J Mol Biol. 2003 Jun 13;329(4):815-29
12787680
Mol Pharmacol. 1999 May;55(5):910-20
10220570
Nat Methods. 2008 Aug;5(8):673-8
18668035
J Comp Neurol. 2000 Feb 7;417(2):181-94
10660896
Proc Natl Acad Sci U S A. 2007 May 1;104(18):7682-7
17452637
Proc Natl Acad Sci U S A. 2007 Jun 26;104(26):10859-64
17578920
J Neuroimmunol. 1991 Nov;34(2-3):89-97
1717506
J Biol Chem. 2008 Jul 25;283(30):21084-92
18490452