ジャーナル: Science / 年: 2018 タイトル: Structure of the yeast oligosaccharyltransferase complex gives insight into eukaryotic N-glycosylation. 著者: Rebekka Wild / Julia Kowal / Jillianne Eyring / Elsy M Ngwa / Markus Aebi / Kaspar P Locher / 要旨: Oligosaccharyltransferase (OST) is an essential membrane protein complex in the endoplasmic reticulum, where it transfers an oligosaccharide from a dolichol-pyrophosphate-activated donor to ...Oligosaccharyltransferase (OST) is an essential membrane protein complex in the endoplasmic reticulum, where it transfers an oligosaccharide from a dolichol-pyrophosphate-activated donor to glycosylation sites of secretory proteins. Here we describe the atomic structure of yeast OST determined by cryo-electron microscopy, revealing a conserved subunit arrangement. The active site of the catalytic STT3 subunit points away from the center of the complex, allowing unhindered access to substrates. The dolichol-pyrophosphate moiety binds to a lipid-exposed groove of STT3, whereas two noncatalytic subunits and an ordered N-glycan form a membrane-proximal pocket for the oligosaccharide. The acceptor polypeptide site faces an oxidoreductase domain in stand-alone OST complexes or is immediately adjacent to the translocon, suggesting how eukaryotic OSTs efficiently glycosylate a large number of polypeptides before their folding.
凍結剤: ETHANE-PROPANE / チャンバー内湿度: 95 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK IV 詳細: Quantifoil carbon grids (300 mesh, copper) were glow discharged at 25 mA for 40 s. 3.5 ul of nanodisc-reconstituted OST sample at concentration of 0.5 mg/ml was applied onto the grid and ...詳細: Quantifoil carbon grids (300 mesh, copper) were glow discharged at 25 mA for 40 s. 3.5 ul of nanodisc-reconstituted OST sample at concentration of 0.5 mg/ml was applied onto the grid and grids were blotted for 3 s and flash-frozen in a mixture of liquid ethane and propane cooled by liquid nitrogen..
詳細
OST complex reconstituted into nanodisc
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
特殊光学系
エネルギーフィルター - 名称: GIF Quantum LS
撮影
フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k) 撮影したグリッド数: 2 / 実像数: 3915 / 平均露光時間: 0.25 sec. / 平均電子線量: 2.0 e/Å2
電子線
加速電圧: 300 kV / 電子線源: FIELD EMISSION GUN
電子光学系
C2レンズ絞り径: 100.0 µm / 照射モード: FLOOD BEAM / 撮影モード: BRIGHT FIELD / Cs: 2.7 mm