Requirement of the calcium channel beta subunit for functional conformation.

The cardiac dihydropyridine-sensitive L-type calcium channel was stably expressed in Chinese hamster ovary cells by transfecting the rabbit cardiac calcium channel alpha 1 subunit cDNA with or without coexpression of the beta subunit of skeletal muscle calcium channel. Whereas coexpression of the beta subunit significantly increased DHP binding activity and calcium channel activity, it did not affect the amount of the alpha 1 subunit expressed, as judged by RNA blot hybridization analysis and immunoblotting analysis. The results suggest that association with the beta subunit is necessary for the alpha 1 subunit protein to take a proper conformation suitable for a functional calcium channel.