Abstract from: Biochemical and Biophysical Research Communications
Volume 343, Issue 2, 5 May 2006, Pages 525-534
Toshihiko Ogura (a,b), Kazuhiro Mio (a), Ikuo Hayashi (c), Hiroyuki Miyashita (c), Rie Fukuda (d), Raphael Kopan (e,f), Tatsuhiko Kodama (d), Takao Hamakubo (d), Takeshi Iwastubo (c), Taisuke Tomita (c),*, Chikara Sato (a),*
(a) Neuroscience Research Institute and Biological Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-4, Tsukuba, Ibaraki 305-8568, Japan
(b) PRESTO, Japan Science and Technology Agency, 4-1-8, Honcho Kawaguchi, Saitama, Japan
(c) Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
(d) Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, #35 4-6-1 Komaba, Meguro, Tokyo 153-8904, Japan
(e) Department of Molecular Biology and Pharmacology, Washington University, St. Louis, MO 63110, USA
(f) Department of Medicine, Washington University, St. Louis, MO 63110, USA.
γ- Secretase belongs to an atypical class of aspartic proteases that hydrolyzes peptide bonds within the transmembrane domain of substrates,including amyloid-b precursor protein and Notch. c-Secretase is comprised of presenilin, nicastrin, APH-1, and PEN-2 which form a large multimeric membrane protein complex, the three-dimensional structure of which is unknown. To gain insight into the structure of this complex enzyme, we purified functional c-secretase complex reconstituted in Sf9 cells and analyzed it using negative stain electron microscopy and 3D reconstruction techniques. Analysis of 2341 negatively stained particle images resulted in the three-dimensional representation of c-secretase at a resolution of 48 Å. The structure occupies a volume of 560 · 320 · 240 Å and resembles a flat heart comprised of two oppositely faced, dimpled domains. A low density space containing multiple pores resides between the domains. Some of the dimples in the putative transmembrane region may house the catalytic site. The large dimensions are consistent with the observation that γ-secretase activity resides within a high molecular weight complex.