(A) Stopped-flow assay measuring relative rates of lactic acid transport into reconstituted vesicles containing wild-type or mutant transporter (green, control with empty vesicles; red, wild-type; blue, K35A; cyan, F90A; magenta, F94A; yellow, K177A; olive green, H230A; and gray, H230N). (B) Relative rates of lactic acid transport based on reswelling rates of proteoliposomes. Each data point is an average of five different light scattering data sets. Error bars depict standard deviation for these five light scattering data. All of the transport rates from the mutant transporters are significantly different compare from that of wild-type PfFNT (K35A, P = 2.8 x 10-3; F90A, P = 4.4 x 10-7; F94A, P = 4.9 x 10-6; K177A, P = 1.2 x 10-3; H230A, P = 4.5 x 10-7; H230N, P = 2.0 x 10-6; student's t-test) (green, control with empty vesicles; red, wild-type; blue, K35A; cyan, F90A; magenta, F94A; yellow, K177A; olive green, H230A; and gray, H230N). 