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Presenilin complexes with the C-terminal fragments of amyloid precursor protein at the sites of amyloid beta-protein generation.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2000 Aug 01; Vol. 97 (16), pp. 9299-304. - Publication Year :
- 2000
-
Abstract
- An unusual intramembranous cleavage of the beta-amyloid precursor protein (APP) by gamma-secretase is the final step in the generation of amyloid beta-peptide (Abeta). Two conserved aspartates in transmembrane (TM) domains 6 and 7 of presenilin (PS) 1 are required for Abeta production by gamma-secretase. Here we report that the APP C-terminal fragments, C83 and C99, which are the direct substrates of gamma-secretase, can be coimmunoprecipitated with both PS1 and PS2. PS/C83 complexes were detected in cells expressing endogenous levels of PS. The complexes accumulate when gamma-secretase is inactivated either pharmacologically or by mutating the PS aspartates. PS1/C83 and PS1/C99 complexes were detected in Golgi-rich and trans-Golgi network-rich vesicle fractions. In contrast, complexes of PS1 with APP holoprotein, which is not the immediate substrate of gamma-secretase, occurred earlier in endoplasmic reticulum-rich vesicles. The major portion of intracellular Abeta at steady state was found in the same Golgi/trans-Golgi network-rich vesicles, and Abeta levels in these fractions were markedly reduced when either PS1 TM aspartate was mutated to alanine. Furthermore, de novo generation of Abeta in a cell-free microsomal reaction occurred specifically in these same vesicle fractions and was markedly inhibited by mutating either TM aspartate. Thus, PSs are complexed with the gamma-secretase substrates C83 and C99 in the subcellular locations where Abeta is generated, indicating that PSs are directly involved in the pathogenically critical intramembranous proteolysis of APP.
- Subjects :
- Amyloid Precursor Protein Secretases
Amyloid beta-Protein Precursor chemistry
Animals
Aspartic Acid Endopeptidases
Binding Sites
CHO Cells
Cricetinae
Endopeptidases drug effects
Golgi Apparatus metabolism
Humans
Hydrolysis
Presenilin-1
Amyloid beta-Peptides metabolism
Amyloid beta-Protein Precursor metabolism
Membrane Proteins metabolism
Peptide Fragments metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0027-8424
- Volume :
- 97
- Issue :
- 16
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 10922078
- Full Text :
- https://doi.org/10.1073/pnas.97.16.9299