FIGURE 9.

The binding of DIDS to the open conformation of MCT1. The figure shows a side (A) and top (B) view of the extracellular part of the open MCT1 model. The color scheme is the same as that in Fig. 7, except that DIDS is colored according to atom type with the carbon atoms colored gray. The figure shows how one isothiocyanate group of DIDS is in close contact with Lys³⁸, whereas the two sulfonate groups are bound to Lys⁴⁵, Lys²⁸², and Lys⁴¹³. The inset in B shows the numbering of the TM helices in this view.