4H5J

Crystal Structure of the Guanine Nucleotide Exchange Factor Sec12 (P64 form)

4H5J の概要

• エントリーDOI: 10.2210/pdb4h5j/pdb
• 関連するPDBエントリー: 4H5I
• 分子名称: Guanine nucleotide-exchange factor SEC12, POTASSIUM ION (3 entities in total)
• 機能のキーワード: copii vesicle budding, potassium binding site, beta propeller, protein transport
• 由来する生物種: Saccharomyces cerevisiae (yeast)
• 細胞内の位置: Endoplasmic reticulum membrane; Single-pass type II membrane protein: P11655
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 80693.75

構造登録者

McMahon, C.,Jeffrey, P.D.,Hughson, F.M. (登録日: 2012-09-18, 公開日: 2012-11-07, 最終更新日: 2024-11-20)

主引用文献

McMahon, C.,Studer, S.M.,Clendinen, C.,Dann, G.P.,Jeffrey, P.D.,Hughson, F.M.
The structure of sec12 implicates potassium ion coordination in sar1 activation.
J.Biol.Chem., 287:43599-43606, 2012

PubMed Abstract: Coat protein II (COPII)-coated vesicles transport proteins and lipids from the endoplasmic reticulum to the Golgi. Crucial for the initiation of COPII coat assembly is Sec12, a guanine nucleotide exchange factor responsible for activating the small G protein Sar1. Once activated, Sar1/GTP binds to endoplasmic reticulum membranes and recruits COPII coat components (Sec23/24 and Sec13/31). Here, we report the 1.36 Å resolution crystal structure of the catalytically active, 38-kDa cytoplasmic portion of Saccharomyces cerevisiae Sec12. Sec12 adopts a β propeller fold. Conserved residues cluster around a loop we term the "K loop," which extends from the N-terminal propeller blade. Structure-guided site-directed mutagenesis, in conjunction with in vitro and in vivo functional studies, reveals that this region of Sec12 is catalytically essential, presumably because it makes direct contact with Sar1. Strikingly, the crystal structure also reveals that a single potassium ion stabilizes the K loop; bound potassium is, moreover, essential for optimum guanine nucleotide exchange activity in vitro. Thus, our results reveal a novel role for a potassium-stabilized loop in catalyzing guanine nucleotide exchange.

PubMed: 23109340
DOI: 10.1074/jbc.M112.420141

実験手法

X-RAY DIFFRACTION (2.601 Å)