CATHEPSIN-D IS INVOLVED IN THE CLEARANCE OF ALZHEIMERS BETA-AMYLOID PROTEIN

The cerebral deposition of 39-42 residue amyloid beta-protein (A beta) is a histopathological characteristic of Alzheimer's disease. The pre sent study is aimed at finding proteinases responsible for the intrace llular clearance of A beta. The A beta degrading proteinase was purifi ed from rat brain. Aminoterminal sequence analysis indicated the A bet a-degrading proteinase was cathepsin D. Purified cathepsin D hydrolyze d A beta between Phe(19) and Phe(20). Cathepsin D is likely to be invo lved in the intracellular clearance of aggregatable A beta, since A be ta fragments with Phe(20) at the amino-terminus have been reported to be secreted from several lines of cultured cells.