FIGURE 4.
Histogram of the interaction energies (ΔΔGinteract) in kcal mol−1 for the activation of double mutants produced between IIS4S5 and IIS6 in CaV2.3. ΔΔGinteract were calculated as described under “Experimental Procedures” using the ΔGact values for the wt channel and the individual IIS4S5 mutants (see Table 1) as well as the ΔGact values of the individual IIS6 mutants (see supplemental Table S1). Numerical values for the gating properties of the double mutants are shown in Table 2. In the histogram, the double mutants are shown with the IIS4S5 mutant to the left of the IIS6 mutant (going from the N- to the C-terminal). As shown, the pairs of residues V593G/L699G, V593G/A700G, V593G/A702G, S595G/V703G L596G/L699G, L596G/A700G, L596G/I701G, L596G/A702G, L596G/V703G, L596G/D704G, M597G/I701G, and S602G/I701G displayed significant coupling during the activation gating of CaV2.3.