Absence of modulation of the expressed calcium channel α1G subunit by α2δ subunits

1. The modulatory action of the alpha 2 delta subunit on various high-voltage-activated calcium channels has been demonstrated previously. However, wry little is known about auxiliary subunit modulation of low-voltage-activated (LVA) calcium channels. We have examined the modulation of the alpha 1G subunit corresponding to the neuronal T-type calcium channel by the ubiquitously expressed alpha 2 delta-1 and brain-specific alpha 2 delta-3 subunits. 2. The alpha 1G subunit was expressed alone or in combination with either the alpha 2 delta-1 or alpha 2 delta-3 subunit in human embryonic kidney (HEK 293) cells and whole-cell barium currents were measured. The current density-voltage relationships for peak and sustained current, kinetics of current activation and inactivation, voltage dependence of current inactivation and time course of the recovery from inactivation were analysed for each type of expressed channel. No significant difference was found for any of the examined parameters. 3. These results suggest that the LVA alpha 1G channel is not regulated by known auxiliary alpha 2 delta subunits.