title: Rem GTPase interacts with the proximal CaV1.2 C-terminus and modulates calcium-dependent channel inactivation.
abstract: The Rem, Rem2, Rad, and Gem/Kir (RGK) GTPases, comprise a subfamily of small Ras-related GTP-binding proteins, and have been shown to potently inhibit high voltage-activated Ca(2+) channel current following overexpression. Although the molecular mechanisms underlying RGK-mediated Ca(2+) channel regulation remains controversial, recent studies suggest that RGK proteins inhibit Ca(2+) channel currents at the plasma membrane in part by interactions with accessory channel β subunits. In this paper, we extend our understanding of the molecular determinants required for RGK-mediated channel regulation by demonstrating a direct interaction between Rem and the proximal C-terminus of Ca(V)1.2 (PCT), including the CB/IQ domain known to contribute to Ca(2+)/calmodulin (CaM)-mediated channel regulation. The Rem2 and Rad GTPases display similar patterns of PCT binding, suggesting that the Ca(V)1.2 C-terminus represents a common binding partner for all RGK proteins. In vitro Rem:PCT binding is disrupted by Ca(2+)/CaM, and this effect is not due to Ca(2+)/CaM binding to the Rem C-terminus. In addition, co-overexpression of CaM partially relieves Rem-mediated L-type Ca(2+) channel inhibition and slows the kinetics of Ca(2+)-dependent channel inactivation. Taken together, these results suggest that the association of Rem with the PCT represents a crucial molecular determinant in RGK-mediated Ca(2+) channel regulation and that the physiological function of the RGK GTPases must be re-evaluated. Rather than serving as endogenous inhibitors of Ca(2+) channel activity, these studies indicate that RGK proteins may play a more nuanced role, regulating Ca(2+) currents via modulation of Ca(2+)/CaM-mediated channel inactivation kinetics.
authors.affiliation: Department of Molecular and Cellular Biochemistry and Physiology, University of Kentucky College of Medicine, Lexington, USA.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Pang
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Crump
authors.forename: Ling
authors.initials: L
authors.lastname: Jin
authors.forename: Robert N
authors.initials: RN
authors.lastname: Correll
authors.forename: Brian S
authors.initials: BS
authors.lastname: Finlin
authors.forename: Jonathan
authors.initials: J
authors.lastname: Satin
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Andres
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002147:Calmodulin; D007700:Kinetics; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D018631:ras Proteins / Q000378:metabolism
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D002147:Calmodulin; C108135:Rem protein, mouse; C490030:Rrad protein, mouse; D020559:Monomeric GTP-Binding Proteins; C517391:Rem2 protein, mouse; D018631:ras Proteins; D002118:Calcium
references.citation: Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12448-52
references.pmid: 7809057
references.citation: Trends Neurosci. 1998 Apr;21(4):148-54
references.pmid: 9554724
references.citation: Cardiovasc Res. 2007 Mar 1;73(4):641-7
references.pmid: 17137569
references.citation: Science. 1995 Dec 1;270(5241):1502-6
references.pmid: 7491499
references.citation: Annu Rev Cell Dev Biol. 2000;16:521-55
references.pmid: 11031246
references.citation: EMBO J. 1989 Apr;8(4):1093-8
references.pmid: 2663468
references.citation: J Biol Chem. 1997 Aug 1;272(31):19401-7
references.pmid: 9235939
references.citation: Science. 1994 Jul 8;265(5169):241-4
references.pmid: 7912851
references.citation: Circ Res. 2007 Jul 6;101(1):69-77
references.pmid: 17525370
references.citation: Sci STKE. 2006 Jan 17;2006(318):er1
references.pmid: 16685765
references.citation: J Biol Chem. 1997 Aug 29;272(35):21982-8
references.pmid: 9268335
references.citation: Mol Cell Biochem. 2008 Mar;310(1-2):103-10
references.pmid: 18057997
references.citation: Proc Natl Acad Sci U S A. 2003 Nov 25;100(24):14469-74
references.pmid: 14623965
references.citation: Neuron. 2001 Sep 27;31(6):973-85
references.pmid: 11580897
references.citation: Neuron. 1999 Mar;22(3):549-58
references.pmid: 10197534
references.citation: Nature. 2001 Jun 7;411(6838):701-6
references.pmid: 11395774
references.citation: Biochem J. 2000 Apr 1;347 Pt 1:223-31
references.pmid: 10727423
references.citation: Neuron. 2000 Jan;25(1):177-90
references.pmid: 10707982
references.citation: Science. 2006 Dec 1;314(5804):1458-61
references.pmid: 17095657
references.citation: Cell Signal. 2008 Feb;20(2):400-8
references.pmid: 18068949
references.citation: Proc Natl Acad Sci U S A. 1991 Dec 1;88(23):10778-82
references.pmid: 1720551
references.citation: J Gen Physiol. 2006 Nov;128(5):605-13
references.pmid: 17074979
references.citation: Nat Chem Biol. 2007 Dec;3(12):795-804
references.pmid: 17952065
references.citation: Br J Pharmacol. 2006 Jan;147 Suppl 1:S56-62
references.pmid: 16402121
references.citation: J Biol Chem. 2001 Jun 15;276(24):21089-97
references.pmid: 11274161
references.citation: J Mol Biol. 2006 Jan 6;355(1):34-46
references.pmid: 16298391
references.citation: J Biol Chem. 2006 Aug 18;281(33):23557-66
references.pmid: 16790445
references.citation: Trends Pharmacol Sci. 2004 Dec;25(12):626-32
references.pmid: 15530640
references.citation: Mol Cell Biol. 2001 Nov;21(21):7345-54
references.pmid: 11585916
references.citation: Neuron. 2004 Mar 4;41(5):745-54
references.pmid: 15003174
references.citation: Biochem J. 2005 Aug 15;390(Pt 1):67-75
references.pmid: 15862114
references.citation: Arch Biochem Biophys. 1997 Oct 1;346(1):113-24
references.pmid: 9328291
references.citation: Nature. 1994 Mar 3;368(6466):67-70
references.pmid: 7509046
references.citation: J Biol Chem. 1995 Mar 3;270(9):4805-12
references.pmid: 7876254
references.citation: Circ Res. 2009 Jun 19;104(12):1373-81
references.pmid: 19461046
references.citation: Science. 1993 Nov 26;262(5138):1441-4
references.pmid: 8248782
references.citation: FEBS Lett. 2006 Oct 30;580(25):5959-64
references.pmid: 17052716
references.citation: J Neurosci. 2005 Oct 19;25(42):9762-72
references.pmid: 16237180
references.citation: Circulation. 2007 Dec 18;116(25):2976-2983
references.pmid: 18056528
references.citation: J Bioenerg Biomembr. 2003 Dec;35(6):599-620
references.pmid: 15000522
references.citation: J Biol Chem. 2007 Apr 13;282(15):11509-20
references.pmid: 17303572
references.citation: J Biol Chem. 2007 Jan 19;282(3):1905-15
references.pmid: 17107948
references.citation: Cell. 2006 Nov 3;127(3):591-606
references.pmid: 17081980
references.citation: EMBO J. 1984 Nov;3(11):2581-5
references.pmid: 6096132
references.citation: J Biol Chem. 2007 Sep 28;282(39):28431-28440
references.pmid: 17686775
references.citation: Proc Natl Acad Sci U S A. 2002 Dec 24;99(26):17185-90
references.pmid: 12486220
references.citation: Cell. 1989 Jun 30;57(7):1167-77
references.pmid: 2661017
references.citation: Circ Res. 2000 Dec 8;87(12):1095-102
references.pmid: 11110765
references.citation: J Biol Chem. 1992 Sep 5;267(25):18218-23
references.pmid: 1325462
references.citation: J Biol Chem. 2005 Dec 23;280(51):41864-71
references.pmid: 15728182
references.citation: Trends Cell Biol. 2005 Dec;15(12):640-3
references.pmid: 16242932
references.citation: Methods Enzymol. 2006;407:484-98
references.pmid: 16757347
references.citation: J Cell Sci. 2005 May 1;118(Pt 9):1923-34
references.pmid: 15860732
references.citation: Am J Physiol Heart Circ Physiol. 2006 Oct;291(4):H1959-71
references.pmid: 16648185
references.citation: Nature. 1999 May 13;399(6732):159-62
references.pmid: 10335846
references.citation: J Physiol. 2006 Oct 1;576(Pt 1):87-102
references.pmid: 16809371
references.citation: Cell Signal. 2008 Feb;20(2):292-300
references.pmid: 18042346
references.citation: Trends Pharmacol Sci. 2003 Apr;24(4):167-71
references.pmid: 12707002
references.citation: Biochim Biophys Acta. 2005 Dec 30;1746(3):274-83
references.pmid: 16039730