Global properties of α1A calcium channel subunit expressed by itself and in combination with different β subunits in HEK (293T) cells. Current-voltage relations for α1A, α2δ, βIb (▪), α1A, α2δ, β2a (▴), and α1A, α2δ, β3 (•). Currents were recorded in “standard” extracellular solution. (A) Macroscopic whole-cell barium currents of transiently transfected HEK cells expressing different calcium channel subunits combinations were observed. The barium currents elicited in response to depolarizing steps from a holding potential of −90 mV. α1A in 80 mM extracellular barium step to +20 mV (B), α1A, α2δ, βIb in “standard solution” step to +10 mV (C), α1A, α2δ, β2a (D), and α1A, α2δ, β3 (E) currents in response to the same protocol as in C. Tails currents of α1A, α2δ, and two different β subunits were generated from a pulse to + 10 mV and then step to −110 mV in 10 mV increments every 20 sec, shown are the recordings of tails generated at −80 mV for a α1A, α2δ, β2a (three averaged currents) (F) and α1A, α2δ, βIb (G).