| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Calcium Signals Laboratory, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
Voltage-dependent calcium-channel ß subunits (CaVß) strongly modulate pore-forming 
1 subunits by trafficking channel complexes to the plasma membrane and enhancing channel open probability (Po). Despite their central role, it is unclear whether binding of a single CaVß, or multiple CaVßs, to an 1 subunit governs the two distinct functions. Conventional experiments utilizing coexpression of 1 and CaVß subunits have been unable to resolve the ambiguity due to difficulties in establishing their stoichiometry in functional channels. Here, we unambiguously establish a 1: 1 stoichiometry by covalently linking CaVß2b to the carboxyl terminus of 1C (CaV1.2), creating 1C·ß2b. Recombinant L-type channels reconstituted in HEK 293 cells with 1C·ß2b supported whole-cell currents to the same extent as channels reconstituted via coexpression of the individual subunits. Analysis of gating charge showed 1C·ß2b fully restored channel trafficking to the plasma membrane. Co-transfecting CaVß2a with 1C·ß2b had little further impact on function. To rule out the possibility that fused CaVß2b was interacting in trans with neighbouring 1 molecules, 1C·ß2b was cotransfected with 1B (CaV2.2), and pharmacological block with nimodipine showed an absence of 1B trafficking. These results establish that association of a single CaVß with a pore-forming 1 subunit captures the functional essence of HVA calcium channels, and introduce 1–CaVß fusion proteins as a powerful new tool to probe structure–function mechanisms.
(Received 21 June 2005;
accepted after revision 12 July 2005;
first published online 14 July 2005)
Corresponding author H. M. Colecraft: Calcium Signals Laboratory, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Avenue, 726 Traylor Building, Baltimore, MD 21205, USA. Email: hcolecra{at}bme.jhu.edu
This article has been cited by other articles:
|
|
 |
|
  A. M. Ebert, C. A. McAnelly, A. V. Handschy, R. L. Mueller, W. A. Horne, and D. M. Garrity Genomic organization, expression, and phylogenetic analysis of Ca2+ channel {beta}4 genes in 13 vertebrate species Physiol Genomics, October 7, 2008; 35(2): 133 - 144. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Gonzalez-Gutierrez, E. Miranda-Laferte, D. Nothmann, S. Schmidt, A. Neely, and P. Hidalgo The guanylate kinase domain of the {beta}-subunit of voltage-gated calcium channels suffices to modulate gating PNAS, September 16, 2008; 105(37): 14198 - 14203. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Gonzalez-Gutierrez, E. Miranda-Laferte, D. Naranjo, P. Hidalgo, and A. Neely Mutations of Nonconserved Residues within the Calcium Channel {alpha}1-interaction Domain Inhibit {beta}-Subunit Potentiation J. Gen. Physiol., September 1, 2008; 132(3): 383 - 395. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Miriyala, T. Nguyen, D. T. Yue, and H. M. Colecraft Role of CaV{beta} Subunits, and Lack of Functional Reserve, in Protein Kinase A Modulation of Cardiac CaV1.2 Channels Circ. Res., April 11, 2008; 102(7): e54 - e64. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Chameau, Y. Qin, S. Spijker, G. Smit, and M. Joels Glucocorticoids Specifically Enhance L-Type Calcium Current Amplitude and Affect Calcium Channel Subunit Expression in the Mouse Hippocampus J Neurophysiol, January 1, 2007; 97(1): 5 - 14. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Seu and G. S. Pitt Dose-dependent and Isoform-specific Modulation of Ca2+ Channels by RGK GTPases J. Gen. Physiol., November 1, 2006; 128(5): 605 - 613. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. Crump, R. N. Correll, E. A. Schroder, W. C. Lester, B. S. Finlin, D. A. Andres, and J. Satin L-type calcium channel {alpha}-subunit and protein kinase inhibitors modulate Rem-mediated regulation of current Am J Physiol Heart Circ Physiol, October 1, 2006; 291(4): H1959 - H1971. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Hidalgo, G. Gonzalez-Gutierrez, J. Garcia-Olivares, and A. Neely The {alpha}1-beta-Subunit Interaction That Modulates Calcium Channel Activity Is Reversible and Requires a Competent {alpha}-Interaction Domain J. Biol. Chem., August 25, 2006; 281(34): 24104 - 24110. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Kanevsky and N. Dascal Regulation of Maximal Open Probability Is a Separable Function of Cav{beta} Subunit in L-type Ca2+ Channel, Dependent on NH2 Terminus of {alpha}1C (Cav1.2{alpha}) J. Gen. Physiol., June 26, 2006; 128(1): 15 - 36. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. C. Vendel, C. D. Rithner, B. A. Lyons, and W. A. Horne Solution structure of the N-terminal A domain of the human voltage-gated Ca2+channel beta4a subunit Protein Sci., February 1, 2006; 15(2): 378 - 383. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
