Figure 3.

Arc, β-Spectrin IV (βSpec), and Tip60 form a tight complex. Fluorescently-tagged versions of Arc, β-Spectrin IV, and Tip60 were coexpressed in hippocampal neurons (A−D) or HEK293 cells (E−H) and imaged as described in Fig. 2. Scale bar, 2 μm. I, Arc, βSpIVΣ5, and Tip60 fused to spectrally distinct GFP isoforms were expressed in hippocampal neurons, either individually, as pairs, or all three together. Neuronal nuclei were outlined using DAPI staining and subnuclear structures (puncta) were segmented as described in the Materials and Methods section. For each nucleus, the mean area and number of puncta was calculated. The scatter plot graphs number of puncta versus mean area for the different experiments. Arc, βSpIVΣ5, and Tip60, when expressed alone, each occupy a distinct region of the plot. Paired and tripartite complexes have properties similar to Tip60 alone.