Figure 6. Unitary conductance (γ) of wild-type and T338 mutant CFTRs is related to amino acid side chain size.

Conductances were calculated from the slope of single channel current-voltage relationships (•; see Fig. 4) or from the unitary current at −50 mV estimated from macroscopic current variance (○; see Fig. 5). Mean of data from five to eighteen patches (•) or four to five patches (○). The side chain volume of the amino acid residue present at position 338 was estimated according to Richards (1974).