title: Conserved residues in juxtamembrane region of the extracellular domain of nicastrin are essential for gamma-secretase complex formation.
abstract: The Alzheimer's disease-linked protein, presenilin, forms the active site of the gamma-secretase enzyme complex. However, three other proteins, nicastrin (NCT), PEN-2 and APH-1, are required for enzyme activity. This complex is responsible for cleaving the beta-amyloid precursor protein to produce amyloid beta and the intracellular domain (AICD). Although much research has focused on the regions of presenilin that are important for gamma-secretase function, less is known about NCT. To further our understanding of the role of NCT in gamma-secretase activity and complex formation, we have undertaken a systematic evaluation of conserved residues in the juxtamembrane region of the extracellular domain of NCT. Two mutants, S632A and W648A, greatly reduce gamma-secretase activity, as seen by a reduction in amyloid beta and AICD levels. Several lines of evidence suggest that these mutations result in reduced gamma-secretase activity because they affect the ability of NCT to stably associate with the other gamma-secretase components. Since NCT and APH-1 must first bind in order for presenilin and PEN-2 to stably join the complex, we propose that S632 and W648 are essential for a stable interaction with APH-1.
authors.affiliation: Departments of Psychiatry, Neurology & Genetics, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Walker
authors.forename: Maribel
authors.initials: M
authors.lastname: Martinez
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Alison
authors.initials: A
authors.lastname: Goate
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D000704:Analysis of Variance; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western / Q000379:methods; D016521:Electrophoresis, Gel, Pulsed-Field; D010450:Endopeptidases / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D050505:Mutant Proteins / Q000378:metabolism; D010957:Plasmids / Q000502:physiology; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment / Q000379:methods; D017386:Sequence Homology, Amino Acid; D014162:Transfection / Q000379:methods
chemical_list: D008562:Membrane Glycoproteins; D050505:Mutant Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; C413604:nicastrin protein; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; C509282:Bace1 protein, mouse