Extended Data Fig. 3. Supporting data panels for uptake assays conducted in X. laevis.
a. Uncorrected uptake of IAA over time into X. laevis oocytes. Five individual oocytes were isolated at 2, 4, 6, and 8 min. The transport rate was determined using linear regression. To correct for passive uptake, the slope of water-injected oocytes was subtracted from LAX3-injected oocytes. Data points represent mean +/- SEM with n = 5. b. Radiolabeled IAA or radiolabeled 2,4-D uptake into Xenopus oocytes. Each data point represents the uptake of one individual oocyte. Data are presented as mean values +/- SEM with n = 20. Groups were compared by a two-sided unpaired Student’s t-test (IAA: P < 0.0001; 2,4-D: P < 0.0001). c. Impact of N-terminal truncation on LAX3-mediated IAA corrected uptake into X. laevis oocytes. Each data point represents the uptake of one individual oocyte. Data are presented as mean values +/- SEM with n = 9 (WT), n = 3 (NT trunc.). Groups were compared by a two-sided unpaired Student’s t-test (P = 0.0061). d. Uncorrected data from Fig. 1b. Impact of inhibitors, competitors and proton decouplers on LAX3-mediated IAA uptake into X. laevis oocytes. Uptake of LAX3 and H2O injected oocytes in the presence of 10 µM IAA, 2,4D, 1-NOA and 2-NOA or 1 µM of the proton decouplers 2,4-DNP and FCCP. Each data point represents the uptake of one individual oocyte. Data are presented as mean values +/- SEM with n = 20 (except FCCP, H2O with n = 18). Groups were compared by a two-sided unpaired Student’s t-test (“-“: P < 0.0001; IAA: P < 0.0001; 2,4D: P = 0.0703; 1-NOA: P = 0.0054; 2-NOA: P = 0.0022; 2,4-DNP: P < 0.0001; FCCP: P < 0.0001). e. Uncorrected IAA uptake of LAX3 and H2O injected oocytes at indicated pH. Each data point represents the uptake of one individual oocyte. Data are presented as mean values +/- SEM with n = 20 (except pH 5, H2O with n = 18 and pH 6, H2O with n = 19). Groups were compared by a two-sided unpaired Student’s t-test (pH 5: P < 0.0001; pH 6: P < 0.0001; pH 7.4: P = 0.0396). f. Corrected uptake of IAA mediated by LAX3. Each data point represents the uptake of one individual oocyte. Data are presented as mean values +/- SEM with n = 20. Groups were compared by a one-way ANOVA followed by Tukey’s multiple comparisons test (pH5 vs. pH6: P = 0.0002; pH5 vs. pH7.4: P < 0.0001; pH6 vs. pH7.4: P = 0.0002).