FIGURE 3.

The A343D mutant displaces D-CaM from the NR1a receptor-binding site (fused to the C0C1C2 C-terminal region of the NR1 NMDA receptor, amino acids 818–922) and from the neurogranin-binding site (Nrg, amino acids 1–78). The relative effect of 50 nm GST and GST-Q2 A343D on the relative fluorescence emission from 12.5 nm D-CaM complexed with GST-Nrg (taken as 100%) in the absence of Ca²⁺ (filled bars) and GST-NR1a in the presence of 1.6 μm free Ca²⁺ (empty bars, n = 3) is shown. To make the assay more sensitive, the concentrations of GST-Nrg and GST-NR1a that caused 50% of the maximal increase in D-CaM fluorescence emission were employed (30 and 8.75 nm in the absence -Nrg- and presence -NR1a- of Ca²⁺, respectively). The small effect observed after the addition of 50 nm GST was due to the dilution of the sample.