This gene encodes a member of the peptidase A1 family of aspartic proteases. Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed to generate the mature protease. This transmembrane protease catalyzes the first step in the formation of amyloid beta peptide from amyloid precursor protein. Amyloid beta peptides are the main constituent of amyloid beta plaques, which accumulate in the brains of human Alzheimer's disease patients. Homozygous knockout mice for this gene exhibit a wide range of nervous system defects, growth retardation, metabolic abnormalities, and increased neonatal lethality. [provided by RefSeq, Nov 2015]