Figure 5. Zn²⁺–activation of GlyRs lacking a high affinity glycine binding site.

Glycine (a) and Zn²⁺ (b) concentration response curves on an α1^L134A background with an extra mutation in the glycine binding site (E157A). (c) Maximum currents evoked by glycine (10 mM) and Zn²⁺ (1 mM) for α1^L134A and α1^{L134A, E157A}. Incorporating E157A on an α1^F99A background, ablated activation by up to 10 mM glycine, but induced only a modest, 3–fold decrease in sensitivity to Zn²⁺ activation (d) and no reduction in Zn²⁺ I_max (1 mM) (e) (n = 3–4).