Beta-Secretase

Beta-secretase is a protein family that includes in humans Beta-secretase 1 and Beta-secretase 2. Beta-secretase 1, also known as beta-site amyloid precursor protein cleaving enzyme 1, beta-site APP cleaving enzyme 1 (BACE1), membrane-associated aspartic protease 2, memapsin-2, aspartyl protease 2, and ASP2, is an enzyme that in humans is encoded by the BACE1 gene. Expression of BACE1 is observed mainly in neurons. BACE1 is an aspartic acid protease important in the formation of myelin sheaths in peripheral nerve cells: in mice the expression of BACE1 is high in the postnatal stages, when myelination occurs. The transmembrane protein contains two active site aspartate residues in its extracellular protein domain and may function as a dimer, its cytoplasmic tail is required for the correct maturation and an efficient intracellular trafficking, but doesn't affect the activity. It is produced as a pro-enzyme, the endoproteolitc removal occurs after BACE leaves Endoplasmic reticulum, in the Golgi apparatus. In addition the pro-peptide receives additional sugars to increase the molecular mass. and the tail became a palmitoylated. Beta-secretase 2 (also known as Memapsin-1) is an enzyme that cleaves Glu-Val-Asn-Leu!Asp-Ala-Glu-Phe in the Swedish variant of Alzheimer's amyloid precursor protein. BACE2 is a close homolog of BACE1.