FIGURE 4.
Transport function of wild type HA-hPAT1 and cysteine mutants. A, two-electrode voltage clamp recordings of oocytes injected either with wild type (HA-hPAT1) or mutant HA-hPAT1 cRNA. Water-injected oocytes were used as control. Inward currents induced by 20 mm glycine were determined at pH 6.5. Currents (I20Gly) were calculated as the difference of the currents measured in the presence and absence of glycine. Mean values ± S.E. from measurements of 5 to 6 oocytes are shown. B, uptake of l-[3H]proline (20 nm, 10 min, pH 6.0) was determined in HRPE cells transfected with pSPORT1-HA-hPAT1 (wild type) or the mutant HA-tagged hPAT1 cDNAs in pSPORT1. HRPE cells transfected with the empty vector pSPORT1 served as control. Data are means ± S.E., n = 3–7.