Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by progressive loss of memory and cognition in the elderly. One of the most important and initial step involves proteolytic cleavage of amyloid precursor protein (APP, chromosome 21) releasing short 40, 42 and 43aa peptides (beta amyloid 1-40, 1-42, and 1-43). Polymerization of b-amyloid (Ab) and subsequent neuronal deposit (amyloid) leads to the degeneration of neurons involved in memory and cognition. Ab deposits have also been found to contain 2 additional proteins termed a-synuclein and b-synuclein. The 140aa a-synucleins is identical with non- Ab component (NACP) of AD. The 134aa human b-synuclein is homologous to 14kD bovine phosphoneuroprotein. Mutations in a-synuclein gene causing a replacement of alanine with a threonine may cause the protein to misfold. Synucleins are primarily expressed in the brain. At least 3 forms: two large (140aa SYN-1 and 149aa SYN-2) and a small form (SYN-3, 42aa) are produced by alternative splicing.