NCAM1 but not NCAM2 is a BACE1 substrate in hippocampal synaptosomes of adult mice. Four-month-old BACE1+/+ and BACE1−/− hippocampi were used to isolate the synaptosome using discontinuous sucrose ultracentrifugation. A, representative immunoblot of purified hippocampal synaptosomes using anti-NCAM1 (AF2408), anti-NCAM1 (5B8), anti-NCAM2 (sc-136328), anti-SEZ6 (14E5), anti-CHL1 (AF2147), anti-APP (C1/6.1), anti-BACE1 (D10E5), anti-PSD95 (ab18258), anti-synaptophysin1 (101011), and anti-β-tubulin (2146) antibodies. Increased levels of NCAM1-FL (NCAM1-180 and NCAM1-140), CHL1-FL, APP-FL, and SEZ6-FL were detected in hippocampal synaptosomes. B, graphs represent densitometry of full-length NCAM1 (NCAM1-180, NCAM1-140, and NCAM1-120) protein with anti-NCAM1 (AF2408) or anti-NCAM1 (5B8) antibody normalized to β-tubulin in synaptosome. Unpaired two tailed t-test was used for analysis. ∗p < 0.05, ∗∗p < 0.001, BACE1+/+; n = 5, BACE1−/−; n = 5. N.A., not applicable; ns, not significant.