FIGURE 9.

Valence mapping of the GltPh structure predicts a potential cation binding site with the side chains of Asp³⁶⁷ and Thr¹⁰¹ as ligands. A, valence map for K⁺ (colored dots) in overlay with the GltPh structure. The dots illustrate points in three-dimensional space that were mapped to a valence of 0.8 (blue) to 1.2 (red) (the valence color code is shown on the right side of the figure). An optimal valence of 1 is color-coded green. Thus, green dots indicate a suitable binding site for K⁺, as indicated by the arrows. Residues Thr⁹², Asn³¹⁰, and Asp³¹² of GltPh (Thr¹⁰¹, Asn³⁶⁵, and Asp³⁶⁷ in EAAC1) are highlighted as sticks. B, distances of the coordinating oxygen atom to the center of the cation used for valence calculation.