Coexpression of skeletal muscle voltage-dependent calcium channel alpha 1 and beta cDNAs in mouse Ltk- cells increases the amount of alpha 1 protein in the cell membrane

Coexpression of alpha 1 and beta subunits for all tissue-specific isotypes of calcium channels results in an increase in Ca2+ channel current density and drug receptor function. The quantification of the photoaffinity labeled skeletal muscle alpha 1 subunit polypeptide by two alternative immunoadsorption techniques showed that 3 times higher amount of calcium channel alpha 1 protein appears in the cell membrane when alpha 1 and beta subunits were coexpressed compared to alpha 1 alone. Using Western blotting and immunodetection techniques, we identified two polypeptide bands of alpha 1 with 210 kDa and 170 kD molecular mass, respectively. The combined intensity of these bands was 7-9 times higher when alpha 1 and beta were coexpressed compared to alpha 1 alone. The data provide evidence that coexpression of alpha 1 and beta results in an increased amount of alpha 1 protein in the cell membrane.