The synuclein family includes synuclein-alpha, -beta, and -gamma, and synoretin. These small, highly conserved proteins are localized predominantly in the brain, concentrated in presynaptic nerve terminals. Synuclein-alpha is normally a soluble protein. Abnormal synuclein-alpha forms filamentous inclusions (Lewy bodies and Lewy neurites) in several neurodegenerative diseases, including Parkinson's disease (PD), dementia with Lewy bodies, and Alzheimer's disease. Synucleins beta and gamma (synoretin) associate with synuclein-alpha and inhibit its aggregation.