title: The presenilin 1 protein is a component of a high molecular weight intracellular complex that contains beta-catenin.
abstract: The presenilin (PS) genes associated with Alzheimer disease encode polytopic transmembrane proteins which undergo physiologic endoproteolytic cleavage to generate stable NH2- and COOH-terminal fragments (NTF or CTF) which co-localize in intracellular membranes, but are tightly regulated in their stoichiometry and abundance. We have used linear glycerol velocity and discontinuous sucrose gradient analysis to investigate the distribution and native conformation of PS1 and PS2 during this regulated processing in cultured cells and in brain. The PS1 NTF and CTF co-localize in the endoplasmic reticulum (ER) and in the Golgi apparatus, where they are components of a approximately 250-kDa complex. This complex also contains beta-catenin but not beta-amyloid precursor protein (APP). In contrast, the PS1 holoprotein precursor is predominantly localized to the rough ER and smooth ER, where it is a component of a approximately 180-kDa native complex. PS2 forms similar but independent complexes. Restricted incorporation of the presenilin NTF and CTF along with a potentially functional ligand (beta-catenin) into a multimeric complex in the ER and Golgi apparatus may provide an explanation for the regulated accumulation of the NTF and CTF.
authors.affiliation: Centre for Research in Neurodegenerative Diseases, Departments of Medicine and Medical Biophysics, University of Toronto, Toronto, Ontario M5S 3H2, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Yu
authors.forename: F
authors.initials: F
authors.lastname: Chen
authors.forename: G
authors.initials: G
authors.lastname: Levesque
authors.forename: M
authors.initials: M
authors.lastname: Nishimura
authors.forename: D M
authors.initials: DM
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Levesque
authors.forename: E
authors.initials: E
authors.lastname: Rogaeva
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: Y
authors.initials: Y
authors.lastname: Liang
authors.forename: M
authors.initials: M
authors.lastname: Duthie
authors.forename: P H
authors.initials: PH
authors.lastname: St George-Hyslop
authors.forename: P E
authors.initials: PE
authors.lastname: Fraser
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism*; D001923:Brain Chemistry; D015820:Cadherins / Q000737:chemistry*; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D003598:Cytoskeletal Proteins / Q000737:chemistry*; D004721:Endoplasmic Reticulum / Q000737:chemistry; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010449:Peptide Mapping; D053764:Presenilin-1; D015534:Trans-Activators; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; C508853:PSEN1 protein, human; D010446:Peptide Fragments; D053764:Presenilin-1; D015534:Trans-Activators; D051176:beta Catenin