Figure 5. Met311 is key to the allosteric coupling.

(A) Structural models combining HP2 bound to L-asp and Na⁺ at Na2 site with apo conformation of the NMD motif (left), and apo conformation of HP2 with the NMD motif bound to Na⁺ at Na1 site (right). Met311 and clashing residues in HP2 are shown as sticks and transparent spheres. (B) The dependence of L-asp dissociation constant, K_d, on Na⁺ activity plotted on a log–log scale for mutants within the context of Glt_Phⁱⁿ (left) and unconstrained Glt_Ph (right). The data were fitted to straight lines with slopes shown on the graph or to arbitrary lines for clarity. Dashed lines and corresponding slopes correspond to published dependences for Glt_Phⁱⁿ and Glt_Ph (Reyes et al., 2013).

DOI: http://dx.doi.org/10.7554/eLife.02283.015