Fig. 6.

A mechanical model for sodium-coupled sugar transport. Sodium (green circle) binds first to the extracellular side (‘OUT’; state 1) to open the outer gate (state 2), permitting the sugar (glucose; yellow hexagon) to bind and be trapped in the bound site (state 3). The binding of both substrates induces a conformational change to an ‘inward facing’ conformation, resulting in the opening of the inner gate (state 4) and the release of Na⁺ and sugar into the cell interior. After the release of both substrates, the inner gate closes to form the inward facing ligand-free conformation (state 5). The cycle is completed by the change in conformation to the outward facing ligand-free (state 1). Phlorizin binds at the second point in the process (state 2). Adapted from [6], distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0/). This figure is available as part of a downloadable slideset