Fig. 3. Ion dependence of substrate transport. HeLa cells were transfected either with pBSAMVBC10 carrying the open reading frame of AeaEAAT or with no DNA (–, control), and were assayed for the transport of its substrates, L-glutamate, L-aspartate and D-aspartate, 24 h post infection/transfection. Both A and B are the result of one representative experiment, which was repeated three times and shown to give the same result qualitatively each time. (A) Sodium dependence of substrate transport was assessed by substituting equimolar choline chloride for NaCl in the transport assay buffer (striped bars). (B) Anion dependence of substrate transport was determined by replacing chloride ions in the transport assay buffer either with equimolar concentrations of acetate (gray bars) or gluconate (hatched bars).