Fig. 7
From: AMPA receptors in the synapse turnover by monomer diffusion
Many GluA1 molecules exist as monomers and undergo intermittent transient dimerization/oligomerization in the dendritic-shaft PM. a Representative image sequence of two diffusing Halo7-GluA1 fluorescent spots (labeled with ATTO594; magenta arrowheads) in a dendritic-shaft PM (13 DIV), exhibiting transient colocalization–codiffusion (cyan arrowheads; lasting for 132 ms) (representative results from 205 independent video clips). b The distributions of the colocalization durations of Halo7-GluA1 and Cy3-DOPE (n = 205 and 19 events, respectively) in the dendritic-shaft PM. Each histogram could be fitted as those in Fig. 3d, e. c The distributions of the diffusion coefficients (D200ms) of ACP-GluA1 monomers, homodimers, and homotetramers and ACP-GluA1ΔNTD monomers in the HEK293-PM (left), those of Halo7-GluA1 and Halo7-GluA1ΔNTD in the dendritic-shaft PM (middle), and those of presumed GluA1 monomers, dimers, and tetramers in the dendritic-shaft PM (right; Supplementary Fig. 11a, b). For the breaks at a D200ms of 0.0016 μm2 s−1, see the caption to Supplementary Fig. 7d. Bars, circles, boxes, and whiskers indicate the median values, mean values, interquartile range (25–75%), and 10–90% range, respectively. For whiskers exhibiting diffusion coefficients smaller than 0.0016 μm2 s−1, the 10% values are shown in parentheses. Asterisks and n.s. indicate p < and > 0.05, respectively, using the Brunner–Munzel test (p values: n.s. 1, 0.23; n.s. 2, 0.23; n.s. 3, 0.54; *1, 6.7 × 10−12; *2, <2.2 × 10−16; *3, 1.6 × 10−3; *4, 8.6 × 10−14; *5, 2.9 × 10−12; *6, 1.7 × 10−3; *7, 6.2 × 10−13; *8, 4.4 × 10−7). d The ensemble-averaged MSD plotted against time Δt (see the caption to Supplementary Fig. 7b, c). The plot is linear showing that Halo7-GluA1 underwent simple-Brownian diffusion in the dendritic-shaft PM at a mean diffusion rate between those of hypothetical ACP-GluA1 monomers and dimers (left). Meanwhile it exhibited a saturation, indicating confined diffusion within a confinement domain of 109 nm in the Homer1b-EGFP region (right; see the caption to Supplementary Fig. 12d). For the statistical parameters, see Supplementary Table 10. Related GluA2 data are shown in Supplementary Fig. 12
