Rat brain expresses an alternatively spliced form of the dihydropyridine- sensitive L-type calcium channel α2 subunit

We have cloned and sequenced a cDNA (rB-α2) encoding an α2 subunit of the voltage-sensitive L-type calcium channel (dihydropyridine receptor) of rat brain. The cDNA (3823 base pairs) encodes a protein of 1091 amino acids with a M(r) of 123,822. The deduced amino acid sequence of rB-α2 cDNA is highly similar (95% amino acid identity) to that of rabbit skeletal muscle α2 subunit. The rB-α2 protein is distinct from the previously cloned skeletal muscle α2-subunit protein [Ellis, S. B., Williams, M. E., Ways, N. R., Brenner, R., Sharp, A. H., Leung, A. T., Campbell, K. P., McKenna, E., Koch, W., Hui, A., Schwartz, A. and Harpold, M. M. (1988) Science 241, 1661- 1664] because it contains an insertion of 7 amino acid residues and a deletion of a 19-amino acid segment between putative transmembrane domains 1 and 2. We show that the rB-α2 and skeletal muscle α2-subunit transcripts are the variants produced by alternative splicing of the primary transcript and that they are differentially expressed in brain and skeletal muscle, respectively.