Figure 3.

ZmSUGCAR1 mediated both sucrose and glucose transport by electrophysiology assays. A–C, Current/voltage (I/V) relationships of steady-state currents for ZmSUGCAR1 (A, B) and ZmSUT1 (C) triggered by sucrose and glucose in oocytes. The ionic currents were recorded using the TEVC technique. The oocyte membrane potential was held at −60 mV and test potentials ranging from +60 to −100 mV were applied for 800 ms using a step recording mode. The I/V relationships were obtained by subtracting the I/V curves defined in the absence of sugar from those obtained in the presence of sugar. D, Current/voltage (I/V) relationships of the steady-state currents derived from the whole-cell patch-clamp recordings in HEK293T cells. The cells transfected with empty vector (EGFP) were used as the negative control. Data were presented as mean ± se, and n indicated biologically independent cells. E, Whole-cell patch-clamp recordings in HEK293T cells expressing ZmSUGCAR1. F, H⁺ flux rate in oocytes using NMT/MIFE assays. Oocytes expressing ZmSUT1 were used as positive control for the sucrose-mediated H⁺ influx, and oocytes injected with water were used as negative control. G and H, Kinetics of ZmSUGCAR1 for sucrose and glucose uptake in Xenopus oocytes. The K_m and V_max values were determined from the Michaelis–Menten fit. P < 0.05 indicated significant differences.