Sodium-dependent reorganization of the sugar-binding site of SGLT1.

The sodium-dependent glucose cotransporter SGLT1 undergoes a series of voltage- and ligand-induced conformational changes that underlie the cotransport mechanism. In this study we describe how the binding of external Na changes the conformation of the sugar-binding domain, exposing residues that are involved in sugar recognition to the external environment. We constructed 15 individual Cys mutants in the four transmembrane helices (TMHs) that form the sugar binding and translocation domain.