*2.7. Voltage-Gated Ca*2<sup>+</sup> *Channels*

Neuronal calcium channels are protein complexes formed by a pore-forming *α*1 subunit, one *β* and one *α*2*δ* subunit, the latter regulating membrane trafficking and voltage dependence [170]. There are ten different *α*1 subunits that can be divided into three families (Ca*V*1.x–3.x). Each of these families consists of several subtypes that differ in biophysical parameters, expression pattern and physiological function. In addition, there is a clear distinction in the voltage dependence of Ca*V*1.x and Ca*V*2.x when compared to Ca*V*3.x. While the latter activates at quite hyperpolarized potentials (<−50 mV), thus being termed low voltage activated channel (LVA), the former need much higher depolarizations to be opened and are called high voltage activated channels (HVA). In DRG neurons, all three families of Ca*V*s are found [171] and all can be modulated by GPCRs to different extents. Depending on the type of GPCR, the channels are modulated via different pathways.
