The hydrolytic activity of the gamma secretase complex is responsible for the cleavage of a wide range of substrates, including the amyloid precursor protein (APP) - a proteolytic event that is the final step in the production of the amyloid beta peptide, a protein fragment deposited in the brains of individuals with Alzheimer's disease (AD). This evidence concerns the gene APP and early-onset autosomal dominant Alzheimer disease.