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Stable co‐expression of calcium channel alpha 1, beta and alpha 2/delta subunits in a somatic cell line.
Author(s) -
Welling A,
Bosse E,
Cavalié A,
Bottlender R,
Ludwig A,
Nastainczyk W,
Flockerzi V,
Hofmann F
Publication year - 1993
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1993.sp019926
Subject(s) - interleukin 10 receptor, alpha subunit , chinese hamster ovary cell , interleukin 5 receptor alpha subunit , calcium channel , g alpha subunit , protein subunit , alpha (finance) , voltage dependent calcium channel , dihydropyridine , beta (programming language) , l type calcium channel , r type calcium channel , scn3a , chemistry , microbiology and biotechnology , gamma subunit , biophysics , biology , calcium , biochemistry , t type calcium channel , receptor , gene , medicine , construct validity , nursing , organic chemistry , computer science , programming language , patient satisfaction
1. The high‐voltage‐activated L‐type calcium channel is a multi‐protein complex of alpha 1, alpha 2/delta, beta and gamma subunits. The alpha 1 subunit contains the voltage‐dependent calcium‐conducting pore. Chinese hamster ovary (CHO) cells were stably transfected with the complementary DNA of the alpha 1, beta and alpha 2/delta subunits. These subunits were not detected in wild‐type CHO cells. 2. The alpha 1 (CaCh2b) subunit itself directed the expression of functional calcium channels which bound calcium channel blockers and showed voltage‐dependent activation and inactivation. 3. The co‐expression of the alpha 1 subunit with the beta subunit (CaB1 gene) enhanced the density of the dihydropyridine binding sites 2‐ to 3‐fold and increased dihydropyridine‐sensitive barium inward currents (IBa) up to 3.5‐fold from ‐13.3 microA/cm2 (alpha 1 subunit) to ‐46.7 microA/cm2 (alpha 1 and beta subunits). 4. Co‐expression of the beta subunit did not change the sensitivity of IBa towards dihydropyridines, but accelerated current activation and inactivation and shifted the half‐maximal steady‐state activation and inactivation to slightly more hyperpolarizing potentials. 5. The co‐expression of the alpha 2/delta subunit together with alpha 1 and beta subunits accelerated the inactivation kinetics of the channel without a major effect on the other parameters. 6. These results indicate that the beta and alpha 2/delta subunit interact with the alpha 1 subunit and modulate thereby the properties of the alpha 1 subunit‐dependent inward current.