Fig. 4.
CaVβ-GK slows inactivation of CaV2.3-mediated currents. (A) Representative current traces from oocytes expressing CaV2.3 cRNA alone or after injection of the specified protein during a 10-s pulse to 0 mV from a holding potential of −90 mV. (B) Average decay times to half-peak current amplitude (t½) for the different subunit combinations: CaV2.3 cRNA, t½ = 0.33 ± 0.03 s (n = 26); CaV2.3 + CaVβ2a-GK cRNA, t½ = 0.41 ± 0.05 s (n = 13); CaV2.3 + CaVβ2a-GK, t½ = 1.85 ± 0.44 s (n = 13); CaV2.3 + CaVβ2a-SH3-GK, t½ = 3.57 ± 0.42 s (n = 21); CaV2.3 + CaVβ2a cRNA, t½ = 4.11 ± 0.65 s (n = 12); CaV2.3 + CaVβ2a, t½ = 4.76 ± 0.70 s (n = 16); CaV2.3 + CaVβ2a-SH3, t½ = 0.35 ± 0.04 s (n = 13). The t½ values for CaV2.3 + CaVβ2a-GK, CaV2.3 + CaVβ2a-SH3-GK, and CaV2.3 + CaVβ2a were significantly different from those measured in oocytes expressing CaV2.3 alone (t test; P < .01). (C) Time course of inhibition of inactivation by CaVβ2a-GK. Each bar corresponds to the average t½ measured at different time intervals after protein injection. The first bar includes recordings from 12–50 min (n = 4), and the second bar includes recordings from 51–100 min (n = 6) and every 100 min thereafter (n = 7, 2, and 4, respectively). The dashed line corresponds to t½ for CaV2.3 alone.