Fig. 4: Inhibition of aspartate transport by the sybody.

a Uptake of aspartate in liposomes reconstituted with Glt_Tk using aspartate and Na⁺ concentrations of 1 μM and 300 mM respectively. Uptake traces in the absence of sybody (green), in the presence of 750 nM sybody on the outside (orange), or with sybody present on both sides of the membrane (red). Each data point represents a triplicate measurement (n = 3), and the standard error of the mean is shown. b Cryo-EM structure of the Glt_Tk-sybody complex. Left: cartoon representation of the Glt_Tk protomer (transport domain in blue and the scaffold in yellow) that has the sybody bound (red). The surface of the protein is shown in transparent representation, and the approximate location of the membrane boundaries is indicated with dashed lines. Right: sliced-through representation highlighting that the sybody likely blocks movement of the transport domain along with the scaffold domain. The transport domain is in the intermediate-outward state, as described in ref. ¹³ c, d Same as in Fig. 1a, b for a selection of conditions (using the same color coding), but now in the presence of 750 nM sybody on the outside of the liposomes.