Tissue-specific expression of calcium channels

The high-voltage-activated calcium channel is a multimeric protein complex containing 1, 2/δ, β, and γ subunits. The 1 subunit is the ion conduction channel and contains the binding sites for calcium channel blockers and toxins. Three genes code for distinct L-type, dihydropyridine-sensitive 1 subunits; one gene codes for the neuronal P-type (Purkinje) 1 subunit; and one gene codes for the neuronal N-type 1 subunit. The smooth and cardiac muscle L-type calcium channel 1 subunits are splice variants of the same gene. The 1 subunits are coexpressed with a common 2/δ subunit and tissue-specific β subunits (at least three genes). The γ subunit apparently is expressed only in skeletal muscle. The properties of these cloned and expressed calcium channels are discussed here