Fig. 7

Structural and functional analyses of critical residues on the Ca²⁺ loops. a, b Visualization of the cBest1 Ca²⁺-binding site composed of an N-terminal loop (a) and a Ca²⁺ clasp (b). Critical residues are shown with their side chains. Helices surrounding the critical residues are labeled in the same colors as those in Supplementary Fig. 1 for comparison. Yellow sphere, Ca²⁺. c Visualization of the region corresponding to the Ca²⁺ clasp in KpBest, which is a Zn²⁺-binding site. Critical regions and residues are labeled yellow in wild-type (WT) and green in the L259A mutant. Zn²⁺ sphere is yellow in WT and green in the L259A mutant. d–f Visualization of the structural alterations in KpBest P262A (d), G264A (e), and D269A (f). Critical regions and residues are labeled yellow in WT and green in the mutants. Zn²⁺ sphere is yellow in WT. g Bar chart showing the population steady-state current densities at 100 mV in HEK293 cells expressing WT and the alanine substitution mutants, n = 5-6 for each point. *^,#P < 0.05 compared to currents conducted by WT and untransfected cells, respectively, using two-tailed unpaired Student’s t test. All error bars in this figure represent s.e.m.