すべてのrasタンパク質はポリイソプレニル化ですが,パルミトイロ化されているのは一部だけです
J F Hancock1, A I Magee, J E Childs
1Section of Cell and Molecular Biology, Royal Cancer Hospital, Chester Beatty Laboratories, London, England.
Cell
|June 30, 1989
まとめ
ラスタンパク質は,C端のシステインでポリイソプレニル化されます. パルミトオライゼーションは他の部位で発生し,生物学的機能に不可欠な膜結合および変換活動を強化します.
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:
- Rasタンパク質は,細胞の成長と分化に関与する重要なシグナル伝達分子です.
- プレニレーションとパルミトイレーションを含む翻訳後の改変は,Ras機能にとって非常に重要です.
- 以前の理解では,Rasタンパク質のC末端システインでパルミトイロ化が起きたと示唆されていた.
研究 の 目的:
- Rasタンパク質の機能におけるポリイソプレニル化とパルミトヨル化の正確な部位と役割を解明する.
- これらの改変がRas膜結合と生物学的活動に与える影響を調査する.
主な方法:
- パルミトイレーションに関与するシステイン残留物を特定するために,変異分析を使用した.
- 改変されたRasタンパク質の生物学的活動と膜関連性を調査した.
- Ras膜の局所化に対するポリイソプレノイド生物合成を阻害する効果を評価した.
主要な成果:
- すべてのRasタンパク質はCys186.6でポリイソプレニル化されています.
- パルミトイロ化は,Cys186.6ではなく,超変性の領域内のシステイン残基で発生します.
- ポリイソプレーニル化されても,パルミトイロ化されていないH-rasは活性であり,薄弱に膜と結合する.
- パルミトオライゼーションは,膜結合率と変換活性を増強する.
- ポリイソプレノイド合成の阻害は,Ras膜結合を廃止する.
結論:
- Cys186のポリイソプレニル化は,Rasの生物学的活動と膜結合に不可欠である.
- 異なるシステイン残基に発生するパルミトイロ化は,膜結合および変換力を調節する.
- これらの発見は,Rasの翻訳後の改変とその機能的結果についての理解を洗練します.
関連する概念動画
Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
Lipids as Anchors
In the plasma membrane, the lipids forming the bilayer can also act as an anchor to tether proteins to the membrane. The three main types of lipid anchors found in eukaryotes are – prenyl groups, fatty acyl groups, and glycosylphosphatidylinositol or GPI groups. Prenyl and fatty acyl groups act as anchors on the cytosolic surface of the membrane, whereas GPI anchors proteins on the extracellular side.
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains the...
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains the...
Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
The Ras Gene
The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
Ras is a superfamily...
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...
Protein Modifications in the RER
Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.


