酵母Secタンパク質の組み立ては,エンドプラズマの網膜に転位し,膜に結合した多サブユニット複合体になる
R J Deshaies1, S L Sanders, D A Feldheim
1Division of Biochemistry and Molecular Biology, University of California Berkeley 94720.
Nature
|February 28, 1991
まとめ
この研究では,分泌タンパク質がエンドプラズマ網膜 (ER) に転位するのに不可欠なタンパク質複合体を特定しました. SEC61,SEC62,SEC63遺伝子は,この重要なER膜複合体の成分をコードしています.
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:
- エンドプラズマ網膜 (ER) への分泌タンパク質の転位は,基本的な細胞プロセスです.
- このプロセスは,統合膜タンパク質によって促進されると考えられています.
- 以前の遺伝子研究では,この経路に関与する重要なSaccharomyces cerevisiae遺伝子 (SEC61, SEC62, SEC63) を特定しました.
研究 の 目的:
- 分泌タンパク質のERへの転位の分子メカニズムを調査する.
- SEC61,SEC62,SEC63でコードされるタンパク質とその相互作用を特徴づける.
- これらの遺伝子の役割が,ER ルーメンにタンパク質の輸入を容易にするというのを確認するために.
主な方法:
- 重要な遺伝子を特定するためにSaccharomyces cerevisiaeの遺伝子選択.
- タンパク質の構造を予測するためのDNAシーケンシング.
- SEC62タンパク質の生化学的特徴 (Sec62).
- タンパク質複合体の組成の分析.
主要な成果:
- SEC61,SEC62,SEC63の変異は,ER ルーメンへのタンパク質輸入をブロックすることが判明しました.
- SEC62とSEC63の遺伝子配列は,多発性膜タンパク質を予測する.
- 生物化学的データは,Sec62がER膜タンパク質の一部であることを確認した.
- SEC61,SEC62,SEC63のタンパク質は,他の2つのタンパク質と組み合わさって,多サブユニットの膜関連複合体を形成する.
結論:
- SEC61,SEC62,SEC63のタンパク質は複合体として機能する.
- この多サブユニット複合体は,分泌タンパク質のERへの転位を促進するために不可欠です.
- この発見は,これらのSEC遺伝子がタンパク質の輸入において協力的に作用するという仮説を裏付けている.
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.


