Figure 5.

(A) Exchange of d-[³H]aspartate in proteoliposomes prepared from HeLa cells expressing wild-type (WT) (Left) or Y403F (Right) transporters. The medium contained 120 mM Tris phosphate (pH 7.4) with and without 10 mM l-aspartate. Trans-l-aspartate-dependent exchange is shown in external medium containing 150 mM NaCl, 150 mM LiCl, or 150 mM choline chloride as indicated. (B) Ion specificity of exchange of d-[³H]aspartate in wild-type or Y403F transporters. Conditions are as in A, where the chloride salts of the indicated cations at 150 mM are added to the external medium.