Figure 1.

Transport activity of heterologously expressed His₆-tagged GlyTs. Oocytes injected with 25 ng of the indicated cRNAs or water were kept at 19°C for 48 h. Groups of four oocytes each were then incubated with 10 μM [³H]glycine in the absence (open column) or presence (closed column) of 1 mM sarcosine for determination of [³H]glycine uptake. The data show the means ± SD from four groups of oocytes for each experimental condition, with uptake values of 28.7 ± 3.4 and 19.3 ± 1.2 pmol/oocyte/h for His-GlyT1 and GlyT1-His, and of 19.7 ± 2.9 and 20.1 ± 3.2 pmol/oocyte/h for His-GlyT2 and GlyT2-His, respectively. These values correspond to 60–129% of the uptake found with the wild-type GlyT1 and GlyT2 proteins under identical conditions. Statistically significant differences between oocytes incubated with and without sarcosine are indicated (*, P < 0.01).