Figure 8. Relationship between the permeability of intracellular lyotropic anions and their mean diameters, in wild-type and T338 mutant CFTRs.

Permeability ratios (P_X/P_Cl) for SCN⁻, NO₃⁻, Br⁻, Cl⁻, I⁻, ClO₄⁻, benzoate and PF₆⁻ were taken from Table 1; ionic diameters are as calculated previously (Linsdell & Hanrahan, 1998). In each case the data have been fitted using eqn (2) (see Methods), giving estimates of the functional pore diameter (d) of 0.528 nm for wild-type, 0.576 nm for T338A, 0.549 nm for T338S, 0.510 nm for T338N and 0.540 nm for T338V. Anions examined (in order of increasing diameter) were: SCN⁻, Cl⁻, NO₃⁻, Br⁻, I⁻, ClO₄⁻, benzoate and PF₆⁻.