Figure 1. Interaction between NR1 and importin α. A, Immunostaining of hippocampal neurons (21 DIV) with anti-NR1 (red) and anti-importin α (green) antibodies reveals partial colocalization in spines (arrowheads) of neurons silenced with TTX (1 μm). Following glutamate stimulation (40 μm, 15 min), the concentration of importin α is decreased in spines and dendrites and increased in the nucleus. Scale bars, 20 μm. B, Quantification of the percentage of NR1-immunopositive spines containing importin α immunoreactivity. *p < 0.05, **p < 0.01, one-way ANOVA F(3,17) = 4.73, p < 0.05. Post hoc least significant difference test was performed to compare all groups (*p < 0.05); n (number of cells) for each category is given below the graph. C, IB of adult rat forebrain homogenate (fb), synaptosome (syn), and PSD fractions (equal protein concentrations) with importin α and NR1 antibodies shows that both proteins are present in synaptosome and PSD fractions. Synaptophysin (p38), Synaptosome marker; PSD-95, PSD marker. D, NR1 and importin α co-IP from adult fb and syn. IPs were performed with monoclonal anti-NR1 antibodies or with polyclonal anti-importin α antibodies, and immunoblots with polyclonal anti-importin α antibodies or with monoclonal anti-NR1 antibodies, respectively. Control immunoprecipitates included monoclonal anti-GFP antibodies (for NR1) or pre-immune rabbit serum (for importin α). Anti-GAPDH antibodies were used as controls for IB. Experiments in C and D were replicated three times.