Structural basis of human γ-secretase assembly

Proc Natl Acad Sci U S A. 2015 May 12;112(19):6003-8. doi: 10.1073/pnas.1506242112. Epub 2015 Apr 27.


The four-component intramembrane protease γ-secretase is intricately linked to the development of Alzheimer's disease. Despite recent structural advances, the transmembrane segments (TMs) of γ-secretase remain to be specifically assigned. Here we report a 3D structure of human γ-secretase at 4.32-Å resolution, determined by single-particle, electron cryomicroscopy in the presence of digitonin and with a T4 lysozyme fused to the amino terminus of presenilin 1 (PS1). The overall structure of this human γ-secretase is very similar to that of wild-type γ-secretase determined in the presence of amphipols. The 20 TMs are unambiguously assigned to the four components, revealing principles of subunit assembly. Within the transmembrane region, PS1 is centrally located, with its amino-terminal fragment (NTF) packing against Pen-2 and its carboxyl-terminal fragment (CTF) interacting with Aph-1. The only TM of nicastrin associates with Aph-1 at the thick end of the TM horseshoe, and the extracellular domain of nicastrin directly binds Pen-2 at the thin end. TM6 and TM7 in PS1, which harbor the catalytic aspartate residues, are located on the convex side of the TM horseshoe. This structure serves as an important framework for understanding the function and mechanism of γ-secretase.

Keywords: Alzheimer’s disease; Presenilin; cryo-EM structure; intramembrane protease; γ-secretase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / metabolism
  • Amyloid Precursor Protein Secretases / chemistry*
  • Catalysis
  • Cell Membrane / metabolism
  • Cryoelectron Microscopy*
  • Detergents / chemistry
  • Digitonin / chemistry
  • Endopeptidases
  • HEK293 Cells
  • Humans
  • Image Processing, Computer-Assisted
  • Membrane Glycoproteins / chemistry
  • Membrane Proteins / chemistry
  • Peptide Hydrolases / chemistry
  • Presenilin-1 / chemistry
  • Protein Binding
  • Protein Structure, Secondary


  • Detergents
  • Membrane Glycoproteins
  • Membrane Proteins
  • PSEN1 protein, human
  • PSENEN protein, human
  • Presenilin-1
  • nicastrin protein
  • APH1A protein, human
  • Amyloid Precursor Protein Secretases
  • Endopeptidases
  • Peptide Hydrolases
  • Digitonin

Associated data

  • PDB/4UIS