まとめ
エンドプラズマ網膜 (ER) は,特定のC端末信号を用いてタンパク質を保持する. Lys-Asp-Glu-Leu (KDEL) 配列は,ERの光タンパク質を誘導し,その分泌を防止する.
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
- タンパク質の密輸 タンパク質の密輸
背景:
- 分泌を目的としたタンパク質は,エンドプラズマ網膜 (ER) を通過する.
- レジデントERタンパク質は,分泌タンパク質と区別する必要があります.
- grp78 (BiP),grp94,およびタンパク質ジスルファイドイソメラーゼのような既知のER光タンパク質は,共通のC末端のLys-Asp-Glu-Leu (KDEL) 配列を共有しています.
研究 の 目的:
- ERタンパク質保持におけるKDEL配列の役割を調査する.
- KDELモチーフがERのローカライゼーション信号として機能するかどうかを判断する.
主な方法:
- grp78 (BiP) の遺伝子操作により,そのC端末が変化する.
- 改変したgrp78とキメリックリゾージムのCOS細胞における発現.
- 細胞ベースの測定法によるタンパク質の局所化と分泌の分析.
主要な成果:
- grp78 C端末の切除または拡張により,その分泌が生じる.
- grp78のC端末配列を持つリゾジーム誘導体は,ERに保持された.
- これらの発見は,KDEL配列がERの局所化に不可欠であることを示しています.
結論:
- Lys-Asp-Glu-Leu (KDEL) 配列は,ERタンパク質保持の信号として作用する.
- このモチーフは,レジデントのERタンパク質と,分泌を目的としたタンパク質を区別する.
- KDEL信号は,おそらく,ERルメン内の特定の保持メカニズムを媒介する.
関連する概念動画
Role of ER in the Secretory Pathway
Eukaryotic cells have a special pathway that enables communication between various intracellular membrane-bound compartments and also with the extracellular environment. This pathway is termed as the secretory pathway.
Components of the secretory pathway
About a third of proteins synthesized in the cell are sorted via the secretory route. They shuffle between different compartments in membrane-bound vesicles until they reach their final destination. The main intracellular compartments involved...
Components of the secretory pathway
About a third of proteins synthesized in the cell are sorted via the secretory route. They shuffle between different compartments in membrane-bound vesicles until they reach their final destination. The main intracellular compartments involved...
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...
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...
GPI Anchoring of Proteins in the ER Membrane
GPI-anchoring is a post-translational, reversible protein modification that is ubiquitous in eukaryotes. Such proteins are primarily present on the exoplasmic leaflet of the plasma membrane.
GPI-anchor structure
A sequence of 11 enzymatic reactions results in the synthesis of the complete GPI anchor consisting of a hydrophobic and a hydrophilic portion. The hydrophobic portion comprises phosphatidylinositol, while the hydrophilic part comprises polar groups like phosphoethanolamine,...
GPI-anchor structure
A sequence of 11 enzymatic reactions results in the synthesis of the complete GPI anchor consisting of a hydrophobic and a hydrophilic portion. The hydrophobic portion comprises phosphatidylinositol, while the hydrophilic part comprises polar groups like phosphoethanolamine,...


