Received July 18, 2002
Accepted after revision September 15, 2002

The ß_1a subunit regulates the functional properties of adult frog and mouse L-type Ca²⁺channels of skeletal muscle

¹ Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del I.P.N., México D.F. 07360, México.
² Department of Pharmacology, Cinvestav Apartado Postal 14-740, México, D.F. 07360, México

^* To whom correspondence should be addressed.

The ß_1a subunit, one of the auxiliary subunits of Ca_V1.1 channels, was expressed in COS-1 cells, purified by electroelution and electrodialysis techniques and identified by Western blot using monoclonal antibodies. The purified ß_1a subunit strongly interacted in vitro with the alpha interaction domain (AID) of Ca_V1.1 channels. The actions of the purified ß_1a subunit on Ca_V1.1 channel currents were assessed in whole cell voltage clamp experiments performed in vesicles derived from frog and mouse adult skeletal muscle plasma membranes. L-type inward currents were recorded in solutions containing Ba²⁺ (I_Ba). Values of peak I_Ba were doubled by the ß_1a subunit in frog and mouse muscle vesicles and the amplitude of the slow component of tail currents was greatly increased. The actions of the ß_1a subunit on Ca_V1.1 channel currents reached a steady state within 20 min. The ß_1a subunit had no effect on the time courses of activation or inactivation of I_Ba or shifted the current-voltage relation. Non-linear capacitive currents were recorded in solutions that contained mostly impermeant ions. Charge movement depended on voltage with average Boltzmann parameters: Q_max = 28.0 ± 6.6 nC µF^-1, V =-58.0 ± 2.0 mV and k = 15.3 ± 1.1 mV (n = 24). In the presence of the ß_1a subunit, these parameters remained unchanged: Q_max = 29.8 ± 3.5 nC µF^-1, V =-54.5 ± 2.2 mV and k = 16.4 ± 1.3 mV (n = 21). Overall, the work describes a novel preparation to explore in situ the role of the ß_1a subunit on function of adult Ca_V1.1 channels.

This article has been cited by other articles:

				Q. Z. Lao, E. Kobrinsky, J. B. Harry, A. Ravindran, and N. M. Soldatov New Determinant for the CaV{beta}2 Subunit Modulation of the CaV1.2 Calcium Channel J. Biol. Chem., June 6, 2008; 283(23): 15577 - 15588. [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. A. Anderson, X. Altafaj, Z. Zheng, Z.-M. Wang, O. Delbono, M. Ronjat, S. Treves, and F. Zorzato The junctional SR protein JP-45 affects the functional expression of the voltage-dependent Ca2+ channel Cav1.1 J. Cell Sci., May 15, 2006; 119(10): 2145 - 2155. [Abstract] [Full Text] [PDF]

				M. C. Garcia, E. Carrillo, J. M. Galindo, A. Hernandez, J. A. Copello, M. Fill, and J. A. Sanchez Short-Term Regulation of Excitation-Contraction Coupling by the {beta}1a Subunit in Adult Mouse Skeletal Muscle Biophys. J., December 1, 2005; 89(6): 3976 - 3984. [Abstract] [Full Text] [PDF]

				S. Dalton, S. X Takahashi, J. Miriyala, and H. M Colecraft A single CaV{beta} can reconstitute both trafficking and macroscopic conductance of voltage-dependent calcium channels J. Physiol., September 15, 2005; 567(3): 757 - 769. [Abstract] [Full Text] [PDF]

				S. J. Dubel, C. Altier, S. Chaumont, P. Lory, E. Bourinet, and J. Nargeot Plasma Membrane Expression of T-type Calcium Channel {alpha}1 Subunits Is Modulated by High Voltage-activated Auxiliary Subunits J. Biol. Chem., July 9, 2004; 279(28): 29263 - 29269. [Abstract] [Full Text] [PDF]

				A. Neely, J. Garcia-Olivares, S. Voswinkel, H. Horstkott, and P. Hidalgo Folding of Active Calcium Channel {beta}1b -Subunit by Size-exclusion Chromatography and Its Role on Channel Function J. Biol. Chem., May 21, 2004; 279(21): 21689 - 21694. [Abstract] [Full Text] [PDF]

				A. Hummer, O. Delzeith, S. R. Gomez, R. L. Moreno, M. D. Mark, and S. Herlitze Competitive and Synergistic Interactions of G Protein {beta}2 and Ca2+ Channel {beta}1b Subunits with Cav2.1 Channels, Revealed by Mammalian Two-hybrid and Fluorescence Resonance Energy Transfer Measurements J. Biol. Chem., December 5, 2003; 278(49): 49386 - 49400. [Abstract] [Full Text] [PDF]

				B. S. Finlin, S. M. Crump, J. Satin, and D. A. Andres Regulation of voltage-gated calcium channel activity by the Rem and Rad GTPases PNAS, November 25, 2003; 100(24): 14469 - 14474. [Abstract] [Full Text] [PDF]

				T. Tada, M. Ohmori, and H. Iida Molecular Dissection of the Hydrophobic Segments H3 and H4 of the Yeast Ca2+ Channel Component Mid1 J. Biol. Chem., March 7, 2003; 278(11): 9647 - 9654. [Abstract] [Full Text] [PDF]