Self‐oligomerization of NACP, the precursor protein of the non‐amyloid β/A4 protein (Aβ) component of Alzheimer's disease amyloid, observed in the presence of a C‐terminal Aβ fragment (residues 25–35)

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Abstract
NACP, the precursor protein of the non‐amyloid β/A4 protein (Aβ) component of Alzheimer's disease (AD) amyloid, also known as α‐synuclein, was suggested to seed amyloid plaque formation in AD by stimulating Aβ aggregation. We have demonstrated that NACP experienced self‐oligomerization only in the presence of a modified Aβ fragment (Aβ25–35) by using dicyclohexylcarbodiimide. This NACP oligomerization, appearing as a discrete ladder on a Tricine SDS‐PAGE, was not observed with other Aβ peptides such as the reverse peptide Aβ35–25 and Aβ1–40, indicating this process was specific not only for the C‐terminal peptide sequence of the Aβ but also for its orientation. It might be, therefore, suggested that the NACP self‐oligomers formed only in the presence of a N‐terminally truncated Aβ peptide could act as a nucleation center for plaque formation during AD development.