Figure 3.

Time course (a) and stereospecificity (b) of Glc-IPM uptake expressed by SAAT1. Xenopus oocytes were injected with 50 nl of water without (squares in a) or with 10 ng of SAAT1-cRNA (circles in a, and all experiments in b) and incubated for 6 days. Uptake of 200 μM [¹⁴C]β-d-Glc-IPM or [¹⁴C]β-l-Glc-IPM was measured after incubating the oocytes for different time periods (a) or for 30 min (b) either in Ori buffer or in Ori buffer containing 175 μM phlorizin. Uptake rates of [¹⁴C]β-d-Glc-IPM and [¹⁴C]β-l-Glc-IPM in SAAT1-cRNA-injected oocytes are shown in b. In oocytes injected with water identical uptake rates for [¹⁴C]β-d-Glc-IPM and [¹⁴C]β-l-Glc-IPM were measured. These rates were insensitive to phlorizin and not significantly different from those in oocytes injected with SAAT1-cRNA in the presence of phlorizin (data not shown). Medians from 8–10 oocytes and SEM are indicated. Typical experiments out of three are presented.