The Beta-Amyloid precursor protein (Beta-APP) is a major constituent of the amyloid deposits in patients with Alzheimer’s disease. The Beta-Amyloid precursor is known to interact with several proteins, including X11 and the G heterotrimetric protein APP-BP1. The neuronal, transmembrane protein X11 is known to bind to the ∫-Amyloid precursor protein via a phosphotyrosine binding (PTB) domain, reducing the secretion of cellular Beta-APP and slowing Beta-APP processing pathways. X11 binds specifically to the YENPTY motif, which is involved in the internalization of Beta-APP. Multiple splice varitents of X11 have been identified, including X11 Alpha (also designated Mint 1), X11 Beta (Mint 2) and X11 Gamma(Mint 3).