人間のSos1は,GRB2に結合するRasのためのグアニンヌクレオチド交換因子であり,GRB2に結合する
P Chardin1, J H Camonis, N W Gale
1Institut de Pharmacologie Moleculaire et Cellulaire, CNRS, Valbonne, France.
まとめ
研究者らは,Ras信号伝達に不可欠なヒトのタンパク質であるhSos1を特定した. グアニンヌクレオチド交換因子として作用し,GRB2と相互作用し,受容体チロシンキナーゼをRas経路に結合させます.
科学分野:
- 分子生物学は分子生物学である.
- 細胞シグナル伝達 細胞信号伝達
- 遺伝学 遺伝学とは
背景:
- ドロソフィラのソス (Son of Sevenless) 遺伝子は,ラスの信号伝達を調節する.
- CDC25は,酵母グアニンヌクレオチド交換因子である.
- 受容体チロシンキナーゼ (RTK) は,Ras信号伝達経路を活性化します.
研究 の 目的:
- ドロソフィラ・ソス. のヒト同型を特定し,特徴づけること.
- Rasシグナル伝達における人間のSosホモログ (hSos1) の機能を決定する.
- hSos1,GRB2,RTKsの相互作用を解明する.
主な方法:
- 補完的なDNA (cDNA) の分離と配列決定.
- 酵母における機能的補完性アッセイ
- In vitro グアニンヌクレオチド交換アッセイ.
- インビヴォおよびインビトロタンパク質相互作用研究 (共免疫プレシピテーション).
主要な成果:
- 広く発現するタンパク質であるhSos1をコードするヒトのcDNAを分離した.
- CDC25に関連したhSos1ドメインが酵母CDC25機能を補完することを実証しました.
- 示されたhSos1は,哺乳類のRasタンパク質におけるグアニンヌクレオチドの交換を刺激する.
- 確認されたhSos1は,GRB2のカルボキシル末端ドメインとGRB2のSH3ドメインを通じてGRB2と相互作用する.
- hSos1.1.を過剰発現する哺乳類の細胞におけるグアニンヌクレオチドの交換活動の増加が観察されました.
結論:
- hSos1は,Rasタンパク質のためのグアニンヌクレオチド交換因子として機能します.
- GRB2-hSos1複合体は,RTKsとRas信号伝達経路の結合を媒介する.
関連する概念動画
GTPases and their Regulation
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Large G-proteins, also known...
Large G-proteins, also known...
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Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
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...
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Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
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...


