Identification of a novel aspartic protease (Asp 2) as beta-secretase.
The Alzheimer's disease beta-amyloid peptide (Abeta) is produced by excision from the type 1 integral membrane glycoprotein amyloid precursor protein (APP) by the sequential actions of beta- and then gamma-secretases. Here we report that Asp 2, a novel transmembrane aspartic protease, has the key activities expected of beta-secretase. Transient expression of Asp 2 in cells expressing APP causes an increase in the secretion of the N-terminal fragment of APP and an increase in the cell-associated C-terminal beta-secretase APP fragment. Mutation of either of the putative catalytic aspartyl residues in Asp 2 abrogates the production of the fragments characteristic of cleavage at the beta-secretase site. The enzyme is present in normal and Alzheimer's disease (AD) brain and is also found in cell lines known to produce Abeta. Asp 2 localizes to the Golgi/endoplasmic reticulum in transfected cells and shows clear colocalization with APP in cells stably expressing the 751-amino-acid isoform of APP.
Hussain
I
I
Department of Neurosciences, SmithKline Beecham Pharmaceuticals, Harlow, Essex, United Kingdom.
Powell
D
D
Howlett
D R
DR
Tew
D G
DG
Meek
T D
TD
Chapman
C
C
Gloger
I S
IS
Murphy
K E
KE
Southan
C D
CD
Ryan
D M
DM
Smith
T S
TS
Simmons
D L
DL
Walsh
F S
FS
Dingwall
C
C
Christie
G
G
D000544:Alzheimer Disease / Q000201:enzymology*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002402:Cathepsin D / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D010450:Endopeptidases; D005260:Female; D006624:Hippocampus / Q000201:enzymology*; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010206:Papain / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D016564:Amyloid beta-Protein Precursor; D011994:Recombinant Proteins; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D010206:Papain; D016282:Aspartic Acid Endopeptidases; C509284:BACE2 protein, human; C509280:BACE1 protein, human; D002402:Cathepsin D