Fig. 3

Syt-1 is a physiological interactor of APP. a Electron microscopic (EM) images of ultra-thin cryosections of naïve PC12 cells show double immunogold labeling of endogenous APP (15 nm) with Syt-1 (10 nm). White arrows depict co-localization of APP with Syt-1 while the inserts show 300 % magnification of APP in close association with Syt-1. Analysis was based on three independent sets of experiments. b Quantitative analysis of immunogold labeling of APP in cluster with Syt-1 compared to APP alone, as revealed by a. c In situ PLA shows interaction between endogenous APP and Syt-1 in naïve PC12 cells. Fluorescence red dots represent close association between APP and Syt-1 (left panel) as compared to the negative control (right panel). Images were taken at identical settings. Nuclear staining with DAPI is shown in blue. Analysis was based on three independent sets of experiments. d Immunofluorescence microscopy images of mouse primary neuronal cultures stained with APP and Syt-1 specific antibodies. Co-localization between APP (green) and Syt-1 (red) was observed in the cell body and in neurites. Images were obtained at identical settings. Analysis was based on three independent sets of experiments