alpha -Synuclein is member of a family of small soluble proteins that include also beta -, and gamma -Synuclein. It is predominantly expressed in neurons of the central nervous system in the presynaptic region of nerve terminals, where cycles between free partially unfolded and helical membrane-bound forms.  alpha -Synuclein can self-aggregate in vivo and in vitro, forming various oligomeric species and fibrillar and amorphous aggregates. The fibrils and amyloidal forms of alpha -Synuclein are major components of Lewy bodies and Lewy neurites and have been linked to the pathogenesis of Parkinson’s disease, Parkinson’s disease dementia, and dementia with Lewy bodies. alpha -Synuclein aggregates can be also found associated with amyloid plaques in Alzheirmer’s disease.