Endogenous α-SYN protein analysis on human brain tissues using single-molecule pull-down assay

Alpha-synuclein (α-SYN) is a central molecule in Parkinson’s disease pathogenesis. Despite several studies, the molecular nature of endogenous α-SYN especially in human brain samples is still not well understood due to the lack of reliable methods and the limited amount of bio-specimens. Here, we introduce α-SYN single-molecule pull-down (α-SYN SiMPull) assay combined with in vivo protein crosslinking to count individual αSYN protein and assess its native oligomerization states from biological samples including human postmortem brains. A SiMPull assay enables us to count the number of immuno-precipitated proteins, and reveal the stoichiometry of protein complexes by single-molecule fluorescence imaging. This powerful assay can be highly useful in diagnostic applications using various specimens for neurodegenerative diseases including Alzheimer’s disease and Parkinson’s disease. peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission. The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/188169 doi: bioRxiv preprint first posted online Sep. 13, 2017;