Presenilin complexes with the C-terminal fragments of amyloid precursor protein at the sites of amyloid β-protein generation

Weiming Xia, William J. Ray, Beth L. Ostaszewski, Talat Rahmati, W. Taylor Kimberly, Michael S. Wolfe, Jimin Zhang, Alison M. Goate, Dennis J. Selkoe

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132 Scopus citations


An unusual intramembranous cleavage of the β-amyloid precursor protein (APP) by γ-secretase is the final step in the generation of amyloid β-peptide (Aβ). Two conserved aspartates in transmembrane (TM) domains 6 and 7 of presenilin (PS) 1 are required for Aβ production by γ-secretase. Here we report that the APP C-terminal fragments, C83 and C99, which are the direct substrates of γ-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 γ-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 γ-secretase, occurred earlier in endoplasmic reticulum-rich vesicles. The major portion of intracellular Aβ at steady state was found in the same Golgi/trans-Golgi network-rich vesicles, and Aβ levels in these fractions were markedly reduced when either PS1 TM aspartate was mutated to alanine. Furthermore, de novo generation of Aβ 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 γ-secretase substrates C83 and C99 in the subcellular locations where Aβ is generated, indicating that PSs are directly involved in the pathogenically critical intramembranous proteolysis of APP.

Original languageEnglish
Pages (from-to)9299-9304
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - 1 Aug 2000
Externally publishedYes


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