FIGURE 4.

Mutations to position 384 inhibit alanine transport currents and amino acid uptake. A, typical transport currents induced by application of 10 mm alanine to non-transfected (control) and SNAT2_WT-, and SNAT2_T384A-expressing cells. The bath solution contained 140 mm NaMes, and the pipette solution contained 140 mm KMes at 0-mV transmembrane potential. B, average 10 mm alanine- and MeAIB-induced transport currents (black and gray bars, left axis) and MeAIB uptake (light gray bars, right axis) in HEK293T cells transiently transfected with vector (pBK-CMV (Δ[1098–1300]), SNAT2 wild-type, and SNAT2_T384A cDNA. Transport of [¹⁴C]MeAIB (40 μm) was measured at 1 min in NaMes-containing buffer. Leak currents were subtracted. The comparatively large error bar of the currents in the SNAT2_WT-expressing cells is caused by the up to 3-fold differences in expression levels between different cells. The black stars (*) indicate statistical significance compared with SNAT2_WT at the p < 0.05 level, as determined by one-way analysis of variance followed by Tukey's post-hoc analysis. Statistical significance versus control currents/uptake is illustrated by the gray star (*). −, no error analysis performed.