FIGURE 6.

A, the primary sequences of IS4-S5, IIS4-S5, IIIS4-S5, and IVS4-S5 of Ca_V3.2 were aligned with S4-S5 of Na_VAb, Na_VRh, K_V1.2, and S4-S5 in domain II of Ca_V2.3 using the T-coffee algorithm. Underlined residues have been identified in previous studies as modulating the channel activation gating; Leu-123 in Na_VAb and Leu-596 in Ca_V2.3. The sequence of residues underlined in Ca_V3.2 designate the residues studied herein. B, bar graphs of the activation energies (ΔΔG_act) for the glycine mutants in IIS4-S5 of Ca_V3.2; ΔΔG_act = ΔG_act,mut − ΔG_act,WT. V907G activated at significantly more negative voltages than the WT channel with a ΔΔG_act = −3.3 ± 0.8 kcal mol⁻¹ (n = 11). The complete sets of numerical values are found in Table 2.