Figure 2.

Negative cooperativity of NMDA receptor currents is Ca²⁺ and CaM dependent. a, Representative unitary currents from cell-attached patches containing two GluN1-2a/GluN2A receptors in the presence of 1.8 mm Ca²⁺, in HEK293 cells pretreated with BAPTA-AM (20 μm, top) or coexpressing YFP-CaM₁₂₃₄ (bottom), and corresponding amplitude histograms superimposed by fitted Gaussian components (red dashed) and probability density function (black). b, Correlations between predicted conductance class occupancies from binomial distribution for each recorded file [P(r)_bi] and measured class occupancies [P(r)] show that intracellular buffering and CaM₁₂₃₄ reduce deviations from independence produced by Ca²⁺ (p determined by F test). c, Distributions of coupling coefficients, *p < 0.05, Mann–Whitney U test.