BACE1 and Alzheimer disease: Thus far, our data indicated that (1) BACE1 localizes to normal mossy fiber terminals of hippocampal region CA3; (2) BACE1 accumulates in dystrophic presynaptic axon terminals surrounding amyloid plaques in the AD and 5XFAD brain; (3) little if any BACE1 localizes to postsynaptic structures, and (4) aberrant microtubule structures are present in regions that lack BACE1.