Voltage-gated Ca²⁺ channels (Ca_V), enable the passage of Ca²⁺ ions in a voltage dependent manner. These heteromeric entities are formed in part by the pore-forming α1 subunit which determines the biophysical and pharmacological properties of the channel¹.

L-type Ca²⁺ channels make up one of three voltage-gated Ca²⁺ channel families. Four different α1 isoforms (Ca_V1.1 to Ca_V1.4) belong to the L-type subfamily. Structurally, each α1 subunit has four homologous domains (I-IV) and each domain has a six transmembrane section. Like many other voltage-gated channels, L-type Ca²⁺ channels have auxiliary subunits which are responsible for modulating the surface expression and properties of the channels^2-5.

Ca_V1.1 is mostly expressed in the skeletal muscle, while Ca_V1.4 is mainly detected in the retina. The expression of both Ca_V1.2 and Ca_V1.3 is more extensive and includes neurons, heart, smooth muscle, inner ear, retina and pancreas⁶. L-type Ca²⁺ channels are involved in and modulate a variety of physiological functions such as muscle contraction, hormone secretion, neuronal excitability and gene expression⁵.

All Ca_V1 channels are influenced by dihydropyridines (DHP) and are also referred to as DHP receptor. Several described peptidyl toxins are specific L-type channels blockers, but so far no selective blocker for Ca_V1 isoforms have been described.