Alzheimer amyloid beta/A4 peptide binding sites and a possible 'APP-secretase' activity associated with rat brain cortical membranes.
We carried out ligand binding experiments on membranes from rat brain cortical grey matter using radioiodinated beta/A4 8-17, with non-specific binding determined by the addition of 10 microM unlabelled peptide. Specific, reversible binding amounted to 60-75% of total binding and showed a clear dependence on time, temperature, pH and membrane concentration. Kinetic analyses indicated a high-affinity binding site with an apparent KD of 440 pM. However, the ligand was partly degraded with loss of the Ser8, Lys16 and Leu17 residues. Excision of the two C-terminal amino acids was inhibited by EDTA, EGTA, dithiothreitol or Zn2+ but was stimulated by Ca2+ or Mn2+. These studies demonstrate high-affinity binding sites for beta/A4 8-17 (or its derivatives) in rat brain, suggesting that this region may contain a physiologically important amino acid sequence and identify a potential membrane-associated amyloid precursor protein (APP) secretase activity.
Allsop
D
D
Department of Molecular Biology, Psychiatric Research Institute of Tokyo, Japan.
Yamamoto
T
T
Kametani
F
F
Miyazaki
N
N
Ishii
T
T
D000544:Alzheimer Disease / Q000201:enzymology*; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002540:Cerebral Cortex / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004355:Drug Stability; D008024:Ligands; D008297:Male; D008566:Membranes / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D016229:Amyloid beta-Peptides; D008024:Ligands; D010455:Peptides