title: Aph-1 interacts at the cell surface with proteins in the active gamma-secretase complex and membrane-tethered Notch.
abstract: The activity of the gamma-secretase complex is critical for the processing of a number of transmembrane proteins, including Notch. Functional gamma-secretase activity can be reconstituted from four proteins--presenilin, nicastrin, Pen-2 and Aph-1--but the role of the individual proteins remains unclear. In this report we describe the cellular localization and protein interactions of Aph-1, with particular regard to Notch receptor processing. We found that Aph-1 is present at the cell surface, where it interacts with Pen-2, the mature forms of presenilin and nicastrin, and full-length Notch. Aph-1 also interacts with a truncated form of Notch, which is a direct substrate for gamma-secretase, but not with the Notch intracellular domain. Immunoprecipitation data for Notch and Aph-1 showed that the Notch-containing gamma-secretase complexes most likely form a small subset of the total number of gamma-secretase complexes. In conclusion, these data demonstrate that Aph-1 is present at the cell surface, presumably in active gamma-secretase complexes, and interacts with the Notch receptor, both before and after ligand activation.
authors.affiliation: Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, Stockholm, Sweden.
authors.forename: Emil M
authors.initials: EM
authors.lastname: Hansson
authors.forename: Kia
authors.initials: K
authors.lastname: Strömberg
authors.forename: Susanne
authors.initials: S
authors.lastname: Bergstedt
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
authors.forename: Jan
authors.initials: J
authors.lastname: Näslund
authors.forename: Johan
authors.initials: J
authors.lastname: Lundkvist
authors.forename: Urban
authors.initials: U
authors.lastname: Lendahl
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; D001324:Autoantigens; D015153:Blotting, Western / Q000379:methods; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006388:Hemagglutinins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D007211:Indoles / Q000378:metabolism; D046911:Macromolecular Substances / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010447:Peptide Hydrolases; D053764:Presenilin-1; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D051880:Receptors, Notch; D014162:Transfection / Q000379:methods
chemical_list: D001324:Autoantigens; C097741:Golgin subfamily A member 2; D006388:Hemagglutinins; D007211:Indoles; C489427:MYC protein, human; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C508853:PSEN1 protein, human; C469349:PSENEN protein, human; D010446:Peptide Fragments; D053764:Presenilin-1; D016271:Proto-Oncogene Proteins c-myc; D051880:Receptors, Notch; C413604:nicastrin protein; C007293:DAPI; C475154:APH1A protein, human; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D010447:Peptide Hydrolases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human