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IN cardiac muscle, where Ca²⁺ influx across the sarcolemma is essential for contraction, the dihydropyridine (DHP)-sensitive L-type calcium channel¹ represents the major entry pathway of extracellular Ca²⁺. We have previously elucidated the primary structure of the rabbit skeletal muscle DHP receptor by cloning and sequencing the complementary DNA². An expression plasmid carrying this cDNA, microinjected into cultured skeletal muscle cells from mice with muscular dysgenesis, has been shown to restore both excitation-contraction coupling and slow calcium current missing from these cells, so that a dual role for the DHP receptor in skeletal muscle transverse tubules is suggested³. We report here the complete amino-acid sequence of the rabbit cardiac DHP receptor, deduced from the cDNA sequence. We also show that messenger RNA derived from the cardiac DHP receptor cDNA is sufficient to direct the …