title: Generation of amyloid beta protein from its precursor is sequence specific.
abstract: Cerebral deposition of amyloid beta protein (A beta) is an early and critical feature of Alzheimer's disease. Here we analyze the substrate requirements of proteases ("beta-secretases") that cleave the beta-amyloid precursor protein (beta APP) at the N-terminus of A beta (Asp-597 of beta APP695) in intact human cells. The cleavage requires a membrane-bound substrate but tolerates shifts in the distance of the hydrolyzed bond from the membrane. The major protease has a minimum recognition region of Val-594 to Ala-598; most substitutions in this sequence strongly decrease or eliminate A beta production. Only the Swedish familial Alzheimer's disease mutation (K595N/M596L) strongly increases A beta production. Moreover, in this mutant but not in the wild type, the entire cytoplasmic tail with its reinternalization signals can be deleted without affecting A beta N-terminal cleavage, consistent with the concept that cleavage of this mutant occurs in a different cellular compartment than that of wild-type molecules. Our results have important implications for current intensive approaches to develop assays for and identify enzymes with beta-secretase activity.
authors.affiliation: Department of Neurology, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115.
authors.forename: M
authors.initials: M
authors.lastname: Citron
authors.forename: D B
authors.initials: DB
authors.lastname: Teplow
authors.forename: D J
authors.initials: DJ
authors.lastname: Selkoe
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000096:biosynthesis* / Q000737:chemistry; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D010450:Endopeptidases / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009447:Neuroblastoma; D009838:Oligodeoxyribonucleotides; D017354:Point Mutation; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D009838:Oligodeoxyribonucleotides; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human