Soluble amyloid beta-protein is a marker of Alzheimer amyloid in brain but not in cerebrospinal fluid.
The amyloid beta protein (A beta), a 4 kD fragment of the beta amyloid precursor protein, is deposited as insoluble amyloid in the brain of Alzheimer disease (AD) subjects. Soluble A beta is a normal metabolic product and is present in cerebrospinal fluid. We identified soluble A beta forms of 4kD, 3kD and 3.7kD in AD but not in control brains free of amyloid deposits. All three forms of soluble A beta extend beyond residue 40. Analysis of cerebrospinal fluid from the same subjects confirmed the presence of only 4kD A beta in comparable amounts in AD and controls. The presence of soluble A beta only in brain regions with amyloid suggests they are related. The undetectability of soluble A beta in control brains indicates that it is normally removed or bound to other proteins. Failure of this protective mechanism might cause amyloid formation in AD.
Tabaton
M
M
Division of Neuropathology, Case Western Reserve University, Cleveland, Ohio 44106-4901.
Nunzi
M G
MG
Xue
R
R
Usiak
M
M
Autilio-Gambetti
L
L
Gambetti
P
P
D000544:Alzheimer Disease / Q000378:metabolism*; D000682:Amyloid / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid / Q000737:chemistry / Q000378:metabolism*; D000911:Antibodies, Monoclonal; D015415:Biomarkers; D001921:Brain / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D012995:Solubility
D000682:Amyloid; D016229:Amyloid beta-Peptides; D000911:Antibodies, Monoclonal; D015415:Biomarkers