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Amyloid precursor protein truncated at any of the γ‐secretase sites is not cleaved to β‐amyloid
Author(s) -
Paganetti Paolo A.,
Lis Maddalena,
Klafki HansWerner,
Staufenbiel Matthias
Publication year - 1996
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19961101)46:3<283::aid-jnr1>3.0.co;2-g
Subject(s) - amyloid precursor protein , secretion , hek 293 cells , amyloid precursor protein secretase , biotinylation , alpha secretase , biochemistry , c terminus , n terminus , signal peptide , peptide sequence , amino acid , p3 peptide , amyloid (mycology) , protein precursor , microbiology and biotechnology , chemistry , biology , enzyme , gene , alzheimer's disease , medicine , inorganic chemistry , disease , pathology
βA4 secretion occurs upon processing of amyloid protein precursor (APP) by β‐secretase (N‐terminus of βA4) and γ‐secretase (C‐terminus). To determine the sequence of these activities and the processing intermediate of βA4, we expressed several truncated APP molecules in human HEK‐293 cells. Immunofluorescence and biotinylation studies indicated that full‐length APP or APP lacking the cytosolic domain both were located intracellularly, associated with the cell surface and secreted. APPs truncated after amino acid 40, 42, or 43 of βA4 were not inserted into cell membranes, were found intracellularly but not on the cell surface, and were efficiently secreted into the culture medium. The secretion of APP truncated at amino acid 40 of βA4 occurred without proteolytic processing. Neither βA4 nor P3 (the product of the α‐secretase) was secreted from any of the APP molecules truncated at the γ‐secretase sites. In sharp contrast to this, when the C‐terminal 100 amino acids of APP were expressed (APP truncated at the N‐terminus of βA4), a robust βA4 secretion was observed. Thus, the C‐terminal fragment of APP produced by β‐secretase activity is likely to be the processing intermediate of βA4. © 1996 Wiley‐Liss, Inc.