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gamma-Secretase: successive tripeptide and tetrapeptide release from the transmembrane domain of beta-carboxyl terminal fragment.
- Source :
-
The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 2009 Oct 14; Vol. 29 (41), pp. 13042-52. - Publication Year :
- 2009
-
Abstract
- Amyloid beta protein (Abeta), a pathogenic molecule associated with Alzheimer's disease, is produced by gamma-secretase, which cleaves the beta-carboxyl terminal fragment (betaCTF) of beta-amyloid precursor protein in the middle of its transmembrane domain. How the cleavage proceeds within the membrane has long been enigmatic. We hypothesized previously that betaCTF is cleaved first at the membrane-cytoplasm boundary, producing two long Abetas, Abeta(48) and Abeta(49), which are processed further by releasing three residues at each step to produce Abeta(42) and Abeta(40), respectively. To test this hypothesis, we used liquid chromatography tandem mass spectrometry (LC-MS/MS) to quantify the specific tripeptides that are postulated to be released. Using CHAPSO (3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxyl-1-propanesulfonate)-reconstituted gamma-secretase system, we confirmed that Abeta(49) is converted to Abeta(43/40) by successively releasing two or three tripeptides and that Abeta(48) is converted to Abeta(42/38) by successively releasing two tripeptides or these plus an additional tetrapeptide. Most unexpectedly, LC-MS/MS quantification revealed an induction period, 3-4 min, in the generation of peptides. When extrapolated, each time line for each tripeptide appears to intercept the same point on the x-axis. According to numerical simulation based on the successive reaction kinetics, the induction period exists. These results strongly suggest that Abeta is generated through the stepwise processing of betaCTF by gamma-secretase.
- Subjects :
- Amyloid beta-Protein Precursor chemistry
Analysis of Variance
Animals
CHO Cells ultrastructure
Cell Membrane drug effects
Cell Membrane metabolism
Cholic Acids pharmacology
Chromatography, Liquid methods
Cricetinae
Cricetulus
Detergents pharmacology
Immunoprecipitation methods
Models, Biological
Oligopeptides chemistry
Oligopeptides metabolism
Peptide Fragments analysis
Protein Structure, Tertiary physiology
Substrate Specificity
Tandem Mass Spectrometry methods
Time Factors
Amyloid Precursor Protein Secretases physiology
Amyloid beta-Peptides chemistry
Amyloid beta-Peptides metabolism
Amyloid beta-Protein Precursor metabolism
Peptide Fragments metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1529-2401
- Volume :
- 29
- Issue :
- 41
- Database :
- MEDLINE
- Journal :
- The Journal of neuroscience : the official journal of the Society for Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 19828817
- Full Text :
- https://doi.org/10.1523/JNEUROSCI.2362-09.2009