**α**_{2}δ-1ΔC-term-HA produces a partial enhancement of calcium channel currents. *A, I-V* relationships for Ca_{V}2.1 plus β1b, either alone (*black squares, n* = 6) or co-expressing either WT α_{2}δ-1 (*black circles, n* = 6) or α_{2}δ-1 mid-HA (*white triangles, n* = 7). Data are mean ± S.E. Data between −30 and + 50 mV were fit with a modified Boltzmann function. The mean *V*_{50, act} values obtained were −4.2, −7.3, and −5.3 mV, respectively. *B, I-V* relationships for Ca_{V}2.1 plus β1b, either alone (*white squares*, *n* = 8) or co-expressing either WT α_{2}δ-1 (*black circles*, *n* = 8) or α_{2}δ-1ΔC-term-HA (*gray triangles*, *n* = 12). Data are mean ± S.E. Data between −30 and + 45 mV were fit with a modified Boltzmann function. The *V*_{50, act} values obtained were −4.1, −4.7, and −5.5 mV, respectively. *C,* representative current traces for the three transfection conditions in response to depolarizing steps from −30 to +10 mV from V_{H} of −90 mV as shown; *calibration bars* refer to all traces. *D,* representative *I*_{Ba} (normalized to the peak current), in response to 900 ms of depolarization to +5 mV, to show differences in inactivation kinetics between Ca_{V}2.1/β1b plus WT α_{2}δ-1 (rapidly inactivating *black trace*), without α_{2}δ (slowly inactivating *black trace*) and with α_{2}δ-1ΔC-term-HA (*gray trace*). *E,* mean τ_{inact} for *I*_{Ba} at +5 mV for WT α_{2}δ-1 (*black bar*, *n* = 7), in comparison with no α_{2}δ (*white bar*, *n* = 5) and α_{2}δ-1ΔC-term-HA (*gray bar, n* = 6). *I*_{Ba} was recorded using 1 mm Ba^{2+}. Statistical differences were determined using one-way analysis of variance and Dunnett's post hoc test, where **, *p* < 0.01, *NS* = nonsignificant.

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