ジャーナル: Elife / 年: 2015 タイトル: Structures of the scanning and engaged states of the mammalian SRP-ribosome complex. 著者: Rebecca M Voorhees / Ramanujan S Hegde / 要旨: The universally conserved signal recognition particle (SRP) is essential for the biogenesis of most integral membrane proteins. SRP scans the nascent chains of translating ribosomes, preferentially ...The universally conserved signal recognition particle (SRP) is essential for the biogenesis of most integral membrane proteins. SRP scans the nascent chains of translating ribosomes, preferentially engaging those with hydrophobic targeting signals, and delivers these ribosome-nascent chain complexes to the membrane. Here, we present structures of native mammalian SRP-ribosome complexes in the scanning and engaged states. These structures reveal the near-identical SRP architecture of these two states, show many of the SRP-ribosome interactions at atomic resolution, and suggest how the polypeptide-binding M domain selectively engages hydrophobic signals. The scanning M domain, pre-positioned at the ribosomal exit tunnel, is auto-inhibited by a C-terminal amphipathic helix occluding its hydrophobic binding groove. Upon engagement, the hydrophobic targeting signal displaces this amphipathic helix, which then acts as a protective lid over the signal. Biochemical experiments suggest how scanning and engagement are coordinated with translation elongation to minimize exposure of hydrophobic signals during membrane targeting.
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集合体
登録構造単位
A: Ribosomal protein uL2 D: Ribosomal protein uL18 G: Ribosomal protein eL8 H: Ribosomal protein uL6 J: Ribosomal protein uL5 L: Ribosomal protein eL13 M: Ribosomal protein eL14 N: Ribosomal protein eL15 O: Ribosomal protein uL13 Q: Ribosomal protein eL18 R: Ribosomal protein eL19 S: Ribosomal protein eL20 T: Ribosomal protein eL21 U: Ribosomal protein eL22 V: Ribosomal protein uL14 X: Ribosomal protein uL23 Y: Ribosomal protein uL24 Z: Ribosomal protein eL27 a: Ribosomal protein uL15 b: Ribosomal protein eL29 c: Ribosomal protein eL30 d: Ribosomal protein eL31 e: Ribosomal protein eL32 f: Ribosomal protein eL33 g: Ribosomal protein eL34 h: Ribosomal protein uL29 i: Ribosomal protein eL36 k: Ribosomal protein eL38 l: Ribosomal protein eL39 m: Ribosomal protein eL40 o: Ribosomal protein eL42 5: 28S ribosomal RNA 7: 5S ribosomal RNA 8: 5.8S ribosomal RNA B: Ribosomal protein uL3 C: Ribosomal protein uL4 E: Ribosomal protein eL6 F: Ribosomal protein uL30 I: Ribosomal protein uL16 P: Ribosomal protein uL22 W: Ribosomal protein eL24 j: Ribosomal protein eL37 n: Ribosomal protein eL41 p: Ribosomal protein eL43 r: Ribosomal protein eL28 K: Ribosomal protein uL11 q: Ribosomal protein uL10 z: SRP54 3: Val tRNA 4: SRP 7S RNA 9: SRP19 6: SRP68 S2: 18S ribosomal RNA SA: Ribosomal protein uS2 SB: Ribosomal protein eS1 SC: Ribosomal protein uS5 SE: Ribosomal protein eS4 SG: Ribosomal protein eS6 SH: Ribosomal protein eS7 SI: Ribosomal protein eS8 SJ: Ribosomal protein uS4 SL: Ribosomal protein uS17 SN: Ribosomal protein uS15 SO: Ribosomal protein uS11 SV: Ribosomal protein eS21 SW: Ribosomal protein uS8 SX: Ribosomal protein uS12 SY: Ribosomal protein eS24 Sa: Ribosomal protein eS26 Sb: Ribosomal protein eS27 Se: Ribosomal protein eS30 SD: Ribosomal protein uS3 SF: Ribosomal protein uS7 SK: Ribosomal protein eS10 SM: Ribosomal protein eS12 SP: Ribosomal protein uS19 SQ: Ribosomal protein uS9 SR: Ribosomal protein eS17 SS: Ribosomal protein uS13 ST: Ribosomal protein eS19 SU: Ribosomal protein uS10 SZ: Ribosomal protein es25 Sc: Ribosomal protein eS28 Sd: Ribosomal protein uS14 Sf: Ribosomal protein eS31 Sg: Ribosomal protein RACK1 S1: SRP9 S4: SRP14 ヘテロ分子
PROTEIN AND RNA IN THIS ENTRY ARE FROM ORYCTOLAGUS CUNICULUS, BUT THE MODELED SEQUENCES ARE FROM SUS SCROFA.
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実験情報
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実験
実験
手法: 電子顕微鏡法
EM実験
試料の集合状態: PARTICLE / ３次元再構成法: 単粒子再構成法
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試料調製
構成要素
ID
名称
タイプ
Parent-ID
別称
1
ScanningribosomeSRPcomplex
RIBOSOME
0
2
80SribosomeEukaryotic ribosome
RIBOSOME
1
mammalianribosome
3
Signalrecognitionparticleシグナル認識粒子
1
SRP
緩衝液
名称: 50 mM HEPES, 200 mM potassium acetate, 15 mM magnesium acetate, 1 mM DTT pH: 7.5 詳細: 50 mM HEPES, 200 mM potassium acetate, 15 mM magnesium acetate, 1 mM DTT
試料
包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES
試料支持
詳細: glow-discharged holey carbon grids (Quantifoil R2/2) coated with a ~70-Angstrom-thick layer of amorphous carbon
急速凍結
装置: FEI VITROBOT MARK IV / 凍結剤: ETHANE / 湿度: 100 % 詳細: 3 uL of sample was incubated on the grid for 30 seconds at 277 K, blotted for 3 seconds, then flash-frozen in liquid ethane (FEI VITROBOT MARK IV). 手法: 3 uL of sample was incubated on the grid for 30 seconds at 277 K before blotting for 3 seconds
ムービー
コントローラー
データを開く
基本情報
要素
キーワード
RIBOSOME (リボソーム) / 
機能・相同性情報
データ登録者
引用
構造の表示
ダウンロードとリンク
その他のダウンロード
PDBj
集合体
分子量: 24.305 Da / 分子数: 166 / 由来タイプ: 合成 / 式: Mg
分子量: 65.409 Da / 分子数: 4 / 由来タイプ: 合成 / 式: Zn
試料調製
電子顕微鏡撮影
解析