RAT-BRAIN EXPRESSES AN ALTERNATIVELY SPLICED FORM OF THE DIHYDROPYRIDINE-SENSITIVE L-TYPE CALCIUM-CHANNEL ALPHA-2 SUBUNIT

We have cloned and sequenced a cDNA (rB-alpha-2) encoding an alpha-2 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-alpha-2 cDNA is highly similar (95% amino acid identity) to that of rabbit skeletal muscle alpha-2 subunit. The rB-alpha-2 protein is distinct from the previously cloned skeletal muscle alpha-2-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. & 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-alpha-2 and skeletal muscle alpha-2-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.