Copatching demonstrates a preferential association between APP and PrP and BACE1 and Thy-1 as well as the relative separation between these two groups. (a) Preferential copatching between endogenous APP and PrP on axons of primary neurons. Mouse hippocampal neurons were treated with rabbit anti-APPex and rat anti–Thy-1.2 or mouse anti-PrP followed by fluorescently labeled secondary antibodies to induce patches of endogenous proteins on neurons. Colocalized APP and PrP patches are indicated by arrowheads. Bar, 5 μm. (b) Quantitative measurements of copatching demonstrated a statistically significant difference between APP–PrP and APP–Thy-1. n = 60. (c and d) Copatching on N2a cells demonstrates a preferential association between APP and PrP or syntaxin 1–HA and BACE1 and Thy-1 as well as the relative separation between these two groups. (c) Copatching is indicated by arrowheads. Bar, 1 μm. Quantitative measurements are shown in panel d. n = 34–44. (b and d) Data are means + SD based on three independent experiments. **, P < 0.01.