Extended Data Fig. 2: Biochemical and biophysical characterization of UMAMIT29 in Xenopus oocytes.

a, 4-methylthiobutyl glucosinolate (4MTB) uptake over time in oocytes expressing UMAMIT29 (UT29) or injected with H₂O (H₂O-inj). Oocytes were incubated for indicated times in 1 mM 4MTB (pH 5.5) and the content was determined in individual oocytes by LC-MS. Data are representative of two independent experiments. b, Current-voltage relationships for an UT29-expressing (UT29) and a H₂O-injected (H₂O-inj) oocyte incubated in Kulori solution with (grey) and without (red) 10 mM 2Propenyl glucosinolate (2Prop) at pH 5.5. c, Effect of pH and extracellular Cl⁻ on UT29-mediated import to oocytes incubated in 1 mM 2Prop for 60 min at pH 5.5 gluconate (Kulori buffer containing 90 mM Na⁺ gluconate instead of 90 mM NaCl), pH 5.5 Cl⁻ and pH 7.4 Cl⁻ (normal Kulori buffer with 95 mM Cl⁻). d–f, Membrane potential of oocytes measured in response to the substitution of anions and cations in Kulori buffer. d, pH 5.5 gluconate, pH 5.5 Cl⁻ and pH 7.4 Cl⁻. e, 100 µM protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) was added into normal Kulori buffer at pH 5.5. f, 91 mM choline⁺ Cl⁻ (Choline⁺) or 91 mM N-methyl-d-glutamine⁺ Cl⁻ (NMDG⁺) were used to substitute 90 mM Na⁺Cl⁻ and 1 mM K⁺Cl⁻ in Kulori buffer, as the sole monovalent ions. Data are mean ± s.d. of individual data points (c,d,e,f) collected from at least two independent experiments or mean ± s.d. of three technical replicates from one representative experiment (b). Statistical analysis was performed using one-way ANOVA with Tukey’s multiple-comparison test (c–f). Bars labelled with different letters are significantly different, p < 0.05).

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