Comparison between the experimental Q-V and G-V characteristics of mutant channels and their respective fitting results with the 10-state allosteric model. (A) 462C466C; (B) 462Y468C. (A) Q-V (open and closed circles) and G-V (triangles) plots from spHCN 462C466C mutant channels (from Fig. 3 A), overlaid with the best fit from the 10-state model (black, red, and green lines; see parameter values in Table 2). (B) Q-V (open and closed squares) and G-V (triangles) plots recorded from 462Y468 mutant channels (from Fig. 4 A), overlaid with the best fit from the 10-state model (black, red, and green lines; see parameter values in Table 2). (A and B) The dotted outline shown in the simple four-state model on the right represents the states of the channel without Cd²⁺, whereas the shaded outline represents the states of the channel with Cd²⁺. Error bars represent SEM.