Amyloid beta A4 protein (beta-amyloid protein) functions as a cell surface receptor and performs physiological functions on the surface of neurons relevant to neurite growth, neuronal adhesion and a, Xenopus/Amphibian,onogenesis. Beta-amyloid protein is involved in cell mobility and transcription regulation through protein-protein interactions. Beta-amyloid protein promotes transcriptional activation through binding to APBB1-KAT5 and inhibits Notch signaling through interaction with Numb. Defects in APP are the cause of Alzheimer disease type 1 (AD1). AD1 is a familial early-onset form of Alzheimer disease. Alzheimer disease is a neurodegenerative disorder characterized by progressive dementia, loss of cognitive abilities, and deposition of fibrillar amyloid proteins as intraneuronal neurofibrillary tangles, e, Xenopus/Amphibian,tracellular amyloid plaques and vascular amyloid deposits.