関連する実験動画
Updated: Jun 30, 2026

09:42
Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides
Published on: June 19, 2012
SecGの膜トポロジーの逆転とSeCA依存型前タンパク質転位を組み合わせた
K Nishiyama1, T Suzuki, H Tokuda
1Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
Cell
|April 5, 1996
まとめ
SecGタンパク質トポロジーの逆転は,E. coliのプレタンパク質トランスロカースの効率化に不可欠です. このプロセスはSecAサイクルと結合し,タンパク質が膜を横断する転位に不可欠です.
科学分野:
- 分子生物学は分子生物学である.
- 細胞生物学 細胞生物学
- バイオケミストリー バイオケミストリー
背景:
- SecAとSecY/E/G複合体で構成されるE. coli前タンパク質トランスロカゼは,内膜にタンパク質の輸送を容易にする.
- SecAは,SecY/Eチャネルにプレタンパク質を供給するために,ATP駆動の膜挿入と脱入のサイクルを使用します.
- SecGは,このトランスロカゼシステムの効率を大幅に高めます.
研究 の 目的:
- プロテイン前転位におけるSecGの役割を調査する.
- 転位時のSecGのダイナミックな行動とトポロジーを解明する.
- SecG,SecaA,およびトランスロカゼ機構の間の機能的結合を理解する.
主な方法:
- SecGのC端末領域に対する抗体を利用し,そのアクセシビリティを検証しました.
- E. coli. のエヴァートされた膜膀を使用した.
- ATPの水解を操作して,転位中間物質を遮断し,観察する.
主要な成果:
- SecGのC端を標的とした抗体が転位を阻害し,その関与を示した.
- SecGのC端末領域は,開始後の転位阻害により,内露状態から外露状態にシフトした.
- 明確なSecG領域はトポロジーの逆転を示し,トランスロケーションとSecAの挿入-脱挿入サイクルと密接に結びついています.
結論:
- SecGは,前タンパク質転位時にトポロジー逆転を経験します.
- SecGにおけるこのダイナミックな形状の変化は,トランスロカゼの効率化に不可欠である.
- SecGの機能サイクルは,SeCAのATPに依存する活動と内在的に結びついている.
関連する概念動画
Cotranslational Protein Translocation
Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
Tail-anchoring of Proteins in the ER Membrane
Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...
Post-translational Translocation of Proteins to the RER
A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.

