The human CACNA1C gene encodes the pore-forming subunits of Cav1.2. Inclusion of auxiliary subunits modulate gating and pharmacological properties, while the inwardly rectifying potassium channel allows the membrane potential to be altered with changes in extracellular K+. Cav1.2 channels expressed in heart, smooth muscle, neurons, and endocrine tissue are therapeutic targets in cardiac arrhythmia and hypertension.