Journal
MOLECULAR AND CELLULAR BIOCHEMISTRY
Volume 310, Issue 1-2, Pages 103-110Publisher
SPRINGER
DOI: 10.1007/s11010-007-9670-8
Keywords
Rem GTPase; RGK; Ras; Ca(V)1.2; voltage-gated calcium channel; calmodulin; L-type calcium channel; VDCC
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Funding
- NCRR NIH HHS [P20 RR20171] Funding Source: Medline
- NHLBI NIH HHS [T32 HL072743, HL072936, HL074091, R01 HL072936] Funding Source: Medline
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GTPases of the Ras-related RGK family are negative regulators of high voltage-activated (HVA) Ca2+ channel activity. In this study, we examined the role of calmodulin (CaM) association in Rem-mediated Ca2+ channel inhibition. We found that the Rem/CaM interaction is Ca2+-dependent, and that truncation of the Rem C-terminus before position 277 prevents CaM binding. Serial mutagenesis of the Rem C-terminus between residues 265 and 276 to alanine generated two mutants (Rem(L271A) and Rem(L274A)) that displayed reduced CaM binding, and a subset of these mutants displayed significantly lower cell periphery localization than Rem(WT). However, reductions in CaM association or membrane trafficking did not affect function, as all Rem mutants could completely inhibit Ca2+ channels. The Rem1-275 truncation mutant partially inhibited Ca2+ channel activity despite its inability to bind CaM. Taken together, these studies indicate that CaM association is not essential for either Rem-mediated Ca2+ channel inhibition or plasma membrane localization.
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