α-Synuclein (accession number NM_000345; known alternatively as NACP, PARK1, and PD1 [Parkinson Disease, familial 1]) is a member of the synuclein family of proteins that also includes β-Synuclein and γ-Synuclein. α-synuclein is highly expressed in several areas of the brain, including the substantia nigra, thalamus, hippocampus, amygdala, corpus callosum, and caudate nucleus, appearing both in neurons where it concentrates at synapses, and in glial cells. Most other tissues, with the exception of liver, express α-synuclein at relatively low levels. Several physiological roles for α-synuclein have been suggested. This protein appears to play a role in dopamine metabolism and vesicle trafficking. It also appears to regulate membrane permeability.