Calcium channels are a class of transmembrane proteins categorized into voltage-gated (L-type, N-type, P/Q-type, R-type, T-type) and ligand-gated types. They are widely distributed in tissues such as the heart, smooth muscle, and neurons, regulating the entry of Ca²⁺ into cells and affecting physiological processes like muscle contraction, neural signal transmission, and secretion. The structure of calcium channels typically includes α₁ subunits, responsible for forming the pore, as well as auxiliary β, α₂δ, and γ subunits. Gene-specific expression and mutations are associated with various diseases, including arrhythmias, hypertension, neuralgia, and genetic disorders. Calcium channel blockers are important drugs for treating hypertension and angina.