Extended Data Fig. 3. Additional evidence for the uniporter model uptake of Glu-Lys into MFSD1/GLMP oocytes.

(a) Combined TEVC and intracellular pH (pH_in) recording of oocytes expressing only the sorting mutant of PQLC2. Lys-Ala (20 mM) is not transported by PQLC2. The traces are representative of four PQLC2 oocytes. (b) The current/acidification relationship of the experiments is shown in Fig. 4a and Extended Data Fig. 3a. The graphs show individual TEVC and pH_in responses to Lys-Ala (10 mM) and His (4 or 20 mM). Each symbol shape represents a distinct oocyte. (c) Representative TEVC and pH_in traces of the response of MFSD1/GLMP oocytes to Lys-Glu. (d) Acidification and current responses normalized to His-Ala and normalized acidification/current ratios. Data are means ± SEM of 4 oocytes. (e) A model accounting for the uptake of Glu-Lys by MFSD1/GLMP. Only uptake of the minor cationic form, Glu⁰-Lys⁺, can be detected in this electrophysiological technique. Source numerical data are available in source data.