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 (RemL271A and RemL274A) that displayed reduced CaM binding, and a subset of these mutants displayed significantly lower cell periphery localization than RemWT. 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.
|Number of pages||8|
|Journal||Molecular and Cellular Biochemistry|
|State||Published - Mar 2008|
Bibliographical noteFunding Information:
Acknowledgments We wish to thank Dr. Carole Moncman for her assistance with the confocal imaging studies and statistical analysis, Dr. Thomas Vanaman for his gift of calmodulin-sepharose resin used in preliminary studies, and members of the Andres lab for critical reading of this manuscript. This work was supported by Public Health Service Grants HL072936 (to DAA), HL074091 (to JS), and P20 RR20171 from the National Center for Research Resources, National Institutes of Health (to DAA), and an American Heart Association pre-doctoral fellowship and an NIH Interdisciplinary Cardiovascular Training Grant T32 HL072743 (to RNC).
- L-type calcium channel
- Rem GTPase
- Voltage-gated calcium channel
ASJC Scopus subject areas
- Molecular Biology
- Clinical Biochemistry
- Cell Biology