まとめ
エンドプラズマ網膜の膜に結晶を形成するリボソームは,新しい構造的詳細を明らかにします. 大型サブユニットの低密度領域は,新生タンパク質のマッピングをします.
科学分野:
- 構造生物学 構造生物学とは
- 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:
- リボソームはタンパク質合成に不可欠です.
- リボソームは,タンパク質合成中にエンドプラズマ網膜膜と相互作用する.
- 以前の研究では,電子結晶学を用いてリボソームの構造を調べた.
研究 の 目的:
- 膜表面上のリボソームサブユニットの配置を解明する.
- リボソーム結晶の原生構造を決定する.
- タンパク質とリボソーム内のリボソームRNA分布の新たな詳細を明らかにする.
主な方法:
- チッキン胚のリボソームから,広大で順番の良いリボソーム結晶を採取した.
- 水性薄膜に結晶を速凍して保存した原生構造.
- 電子結晶学を用いて3次元マップを作成しました.
主要な成果:
- 3次元の地図は,タンパク質とリボソームのRNA分布の新たな詳細を明らかにした.
- 大型リボソームサブユニット内の低密度の顕著な領域を特定しました.
- この低密度領域は,サブユニット界面から,新生タンパク質の膜面の出口部へと広がっている.
結論:
- 低密度領域は,成長するポリペプチドがリボソームを通る経路を線引きしている可能性が高い.
- エンドプラズマの網膜膜のタンパク質転移のメカニズムについての洞察を提供します.
- タンパク質合成中のリボソーム-膜相互作用の理解を深める.
関連する概念動画
Termination of Translation
The large ribosomal subunit has several important structures essential to translation. These include the peptidyl transferase center (PTC) - which is the site where the peptide bond is formed - and a large, internal, water-filled tube through which the nascent polypeptide moves. This latter structure is called the Peptide Exit Tunnel, and it begins at the PTC and spans the body of the large ribosomal subunit. During translation, as the nascent polypeptide chain is synthesized, it passes through...
Directing Proteins to the Rough Endoplasmic Reticulum
The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...
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...
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...
Ribosomes
Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that synthesize large quantities of protein—such as secretory cells in the human pancreas—can contain millions of ribosomes.
Ribosome Structure and Assembly
Ribosomes are composed of ribosomal RNA (rRNA) and proteins. In eukaryotes, rRNA is transcribed from genes in the nucleolus—a part of the nucleus that specializes in ribosome production. Within...
Ribosome Structure and Assembly
Ribosomes are composed of ribosomal RNA (rRNA) and proteins. In eukaryotes, rRNA is transcribed from genes in the nucleolus—a part of the nucleus that specializes in ribosome production. Within...


