Auxiliary subunits: Essential components of the voltage-gated calcium channel complex

Voltage-gated calcium channels are important mediators of several physiological processes, including neuronal excitability and muscle contraction. At the molecular level, the channels are composed of four subunits - the pore forming α₁ subunit and the auxiliary α₂δ, β and γ subunits. The auxiliary subunits modulate the trafficking and the biophysical properties of the α₁ subunit. In the past several years there has been an acceleration of our understanding of the auxiliary subunits, primarily because of their molecular characterization and the availability of spontaneous and targeted mouse mutants. These studies have revealed the crucial role of the subunits in the functional effects that are mediated by voltage-gated calcium channels.