Figure 1.

TrkB receptors interact and colocalize with CPE. A, B, Interaction between TrkB receptors and CPE was assessed in HEK293 overexpressing cDNAs encoding Flag-TrkB, Myc-CPE, and empty vector. Cell lysates were immunoprecipitated (IP) with anti-Flag antibodies (A) or anti-Myc antibodies (B) and immunoblotting (IB) analysis was performed to detect immunoprecipitated proteins. C, Endogenous association of CPE and TrkB receptors. Mice hippocampal tissues lysates were subjected to immunoprecipitation with polyclonal rabbit anti-TrkB antibody or control IgG, followed by immunoblotting with mouse anti-TrkB and mouse anti-CPE antibodies, respectively. A–C, Each co-IP experiment was repeated three times, and representative data are shown. D, Representative immunofluorescence images of the subcellular colocalization of Flag-TrkB and Myc-CPE in hippocampal neurons by confocal microscopy. Lower panels are enlarged images of the framed regions with the white arrows indicating the colocalization of Flag-TrkB and Myc-CPE as shown in yellow. Scale bar, 10 μm. E, Hippocampal neuron cotransfected at DIV 7 with TrkB-GFP and CPE-RFP. Time-lapse images of transport vesicles were acquired at one frame every 20 s for 700 s. F, Corresponding kymographs showing overlapping trajectories of vesicles labeled for TrkB-GFP and CPE-RFP. G, Time-lapse sequence showing a moving vesicle that contains both TrkB-GFP and CPE-RFP, indicated with arrows. Scale bar, 5 µm.