Figure 4.

ω-Conotoxins Bu8, MVIIA, and Bu8 mutants inhibited Ba²⁺ currents mediated by Ca_V2.2 channels co-expressed with cDNAs encoding α1B, β3 and α2δ subunits in HEK293 cells. (A) and (B) Representative traces of whole-cell currents elicited by a voltage step from a holding potential of −90 mV to a test pulse of +20 mV for 100 ms with a 10 s interval per sweep. The time course of normalized currents of I_Ca blocked by Bu8 (A) or MVIIA (B) as indicated. (C) and (D) Concentration–response curves obtained for inhibition of Ca_V2.2 by Bu8, MVIIA, and Bu8 mutants. Whole-cell patch clamp recording from HEK293 cells (n = 3–6). (E) The inhibition and recovery ratio obtained for Bu8 and MVIIA at 2 μmol/L (n > 3). All data are presented as mean ± SEM.