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Modulation of the α1A Ca 2+ channel by β subunits at physiological Ca 2+ concentration
Author(s) -
Cens Thierry,
Mangoni Matteo E.,
Nargeot Joel,
Charnet Pierre
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00704-1
Subject(s) - protein subunit , xenopus , beta (programming language) , biophysics , chemistry , g alpha subunit , alpha (finance) , biology , biochemistry , gene , medicine , construct validity , nursing , computer science , patient satisfaction , programming language
The class A Ca 2+ channel αl subunit (αlA) was expressed in Xenopus oocytes alone or in combination with the βlb, β2a, β3, or β4 subunit. Analysis of voltage‐dependent activation and inactivation in the presence of 1.8 mM external Ca 2+ showed an hyperpolarising shift of both relations when compared to similar recordings performed in the presence of 40 mM Ba 2+ . These shifts, which differed for activation and inactivation, were strongly modulated by the nature of the co‐expressed β subunit. On the other hand, for each combination, the kinetics of inactivation were similar in 1.8 mM Ca 2+ and 40 mM Ba 2+ (for example co‐expression of the β2a subunit reduced inactivation using either 40 mM Ba 2+ or 1.8 mM Ca 2+ ). Thus, modulation of channel properties by the β subunit is different in physiological Ca 2+ or high Ba 2+ concentrations. These results must be taken into consideration to extrapolate the role of the β subunit in native cells.