Effects of mutational factors on parameter identifiability. (A) Scheme illustrating the weakening steps for all fd_y where y runs from 1 to n_D. Using E_x and Z_x illustrated in Fig. S2, the mutational factors fd_y were systematically reduced in 10 steps (weakening factor w = 10…0), providing weakening mutational factors ^wfd_y according to Eq. 21. w = 10 specifies ¹⁰fd_y the maximum mutational effect, as shown in Fig. S2, whereas ⁰fd_y specifies wild type channels with no weakening effect. (B) Plot of the number of successful_p fits as function of w. After performing 250 fits each, the number of successful_p fits was counted by eliminating all fits with physically senseless negative parameters. A weaker mutational effect decreases the number of successful_p fits. At sufficiently strong mutational effects, the CHA⁴ and CHA⁵ model are superior over the CHA² model. (C) Plot of the mean imprecision mipr_np,n as function of w. The mean imprecision (Eq. 12) over all parameters is lower for the CHA⁴ and CHA⁵ model than for the CHA³ model and, particularly, for the CHA² model.