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. 2017 Jan 16;7:40628. doi: 10.1038/srep40628

Figure 4. L-leucine and L-phenylalanine uptake by endogenous Xenopus laevis oocyte and exogenously expressed human sodium-dependent symporter SLC6A14/ATB0,+ and sodium-independent uniporter SLC43A2/LAT4 transporters.

Figure 4

L-Leucine (Leu) uptake rates (pmol/3 min per oocyte) from non-injected (NI) and oocytes expressing human ATB0,+ (hATB0,+) were compared with model calculations. Measured uptake data (pmol/10 min per oocyte) for each batch of oocytes and experimental day was normalized to uptake rates by NI oocytes in 1 mM Leu, +Na+ uptake buffer. Panel (A) shows measured Leu (10–3000 μM) uptake rates for NI oocytes (NI, expt), and for oocytes expressing hATB0,+ without subtraction of NI uptake data (NI+hATB0,+, expt) vs. the calculated model outputs for the respective oocytes (NI, model; and NI+ATB0+, model). Panel (B) shows experimental data for total Leu (0–3000 uM) uptake rates by hATB0,+ expressing oocytes with subtraction of NI oocyte uptake rates (+hATB0,+, expt) vs. calculated Leu uptake by endogenous Xenopus laevis oocyte Leu transporters (xB0AT1, model; and xLAT4, model) and exogenous hATB0,+ transporters (+hATB0,+, model). n = 6–8 oocytes per experiment for 7 independent experiments. Panels (C,D) show L-phenylalanine (Phe) uptake data (pmol/10 min per oocyte) in Na+ containing uptake buffer vs. model calculations for endogenous Phe transporters (xB0AT1, xLAT4, xTAT1) and human LAT4 (hLAT4) transporters. Experimental uptake (pmol/10 min per oocyte) for all oocytes was normalized to uptake in 10 mM Phe, Na+ containing- uptake buffer (Na+). Panel (C) shows normalized total Phe uptake rates by NI oocytes (NI, expt) vs. oocytes with expressed hLAT4 without subtraction of NI oocyte uptake (NI+hLAT4, expt) vs. calculated data for the respective oocyte uptakes (NI, model; and NI+hLAT4, model). Panel (D) shows the normalized data for 0–10 mM Phe uptake rates by oocytes exogenously expressing hLAT4 with subtraction of NI uptake (hLAT4, expt) vs. model calculations for hLAT4 (hLAT4, model) and xAAT Phe transporters (xB0AT1, model; xLAT4, model; and xTAT1, model). n = 6–8 oocytes each experiment for 4 independent experiments. For panels (B,D), 95% confidence limits for predicted transporter activities are shown (dotted lines) bracketing the model predictions for each AAT activity.