Fig. 3.

Dual imaging of p_r and postsynaptic GluR2 level. (A) Example field of view showing surface GluR2 labeling (red, Left), presynaptic FM1-43 signal (green, Center), and merge (Right). Cultured neurons were first live-labeled with anti-GluR2 antibody, and subjected to FM1-43 experiment to examine p_r. FM1-43 was loaded by 30 APs at 1 Hz. (Scale bar, 2 μm.) (B and C) Examples of synaptic areas boxed in A, where FM1-43 and GluR2 signals overlap. Only synapses harboring a single FM1-43 punctum apposed by a single GluR2 punctum were chosen for analysis. (Scale bar, 0.5 μm.) (D and E) Scatter plots of p_r and GluR2 fluorescence intensities at individual synapses from 14–15 DIV (D, n = 88 boutons, five coverslips) and 20–22 DIV neurons (E, n = 54 boutons, five coverslips). Correlation coefficient (r) and P value (p) by Spearman rank correlation test are shown. No apparent correlation is observed for both culture groups. (F and G) Summary plots of GluR2 level versus p_r from D and E. Each point represents an average of five or six synapses, grouped in the order of p_r. Error bars indicate ± SEM. Dotted lines are linear regression fits.