al·pha-sy·nu·cle·in 
(ăl′fə-sĭ-nklē-ĭn, -ny-)
(ăl′fə-sĭ-nklē-ĭn, -ny-)n.
A polypeptide protein found primarily in brain neurons but seen also in the fibrils in Parkinson's disease, in the amyloid plaques of Alzheimer's disease, and in brain tissue affected by other neurodegenerative diseases.