title: Cryoelectron microscopy structure of purified gamma-secretase at 12 A resolution.
abstract: Gamma-secretase, an integral membrane protein complex, catalyzes the intramembrane cleavage of the beta-amyloid precursor protein (APP) during the neuronal production of the amyloid beta-peptide. As such, the protease has emerged as a key target for developing agents to treat and prevent Alzheimer's disease. Existing biochemical studies conflict on the oligomeric assembly state of the protease complex, and its detailed structure is not known. Here, we report that purified active human gamma-secretase in digitonin has a total molecular mass of approximately 230 kDa when measured by scanning transmission electron microscopy. This result supports a complex that is monomeric for each of the four component proteins. We further report the three-dimensional structure of the gamma-secretase complex at 12 A resolution as obtained by cryoelectron microscopy and single-particle image reconstruction. The structure reveals several domains on the extracellular side, three solvent-accessible low-density cavities, and a potential substrate-binding surface groove in the transmembrane region of the complex.
authors.affiliation: Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: Pamela
authors.initials: P
authors.lastname: Osenkowski
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Ye
authors.forename: Dongyang
authors.initials: D
authors.lastname: Li
authors.forename: Lorene
authors.initials: L
authors.lastname: Aeschbach
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Fraering
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wolfe
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Selkoe
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000737:chemistry / Q000648:ultrastructure*; D001665:Binding Sites; D020285:Cryoelectron Microscopy; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008855:Microscopy, Electron, Scanning; D008958:Models, Molecular; D008970:Molecular Weight; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits
chemical_list: D021122:Protein Subunits; D053829:Amyloid Precursor Protein Secretases