Rab GTPasesのTBCドメインのGAPは,双指メカニズムでGTPの水解を加速する
Xiaojing Pan1, Sudharshan Eathiraj, Mary Munson
1Program in Molecular Medicine & Department of Biochemistry and Molecular Pharmacology, UMASS Medical School, Two Biotech, 373 Plantation Street, Worcester, Massachusetts 01605, USA.
Nature
|July 21, 2006
まとめ
GTPase活性化タンパク質 (GAPs) は,RabのGTPase活性を調節する. この研究では,TBCドメインのGAPが,GTP水解を加速するために,アルジニンとグルタミンを含む二指メカニズムを使用して,以前の予想とは異なることを明らかにしました.
科学分野:
- 分子生物学は分子生物学である.
- バイオケミストリー バイオケミストリー
- 細胞生物学 細胞生物学
背景:
- ラブGTP酵素は,膜取引の重要な調節体であり,GDPbound (不活性) とGTPbound (活性) 状態の間で循環する.
- GTP酵素活性化タンパク質 (GAPs) は,GTPの水解を加速することによって,Rab GTP酵素活性状態の持続時間を制御します.
- TBC (Tre-2,Bub2およびCdc16) ドメインのタンパク質は,Rab GTPasesおよび他のGTPasesのための保存された真核GAPです.
研究 の 目的:
- Rab GTPase 調節における TBC ドメイン GAP の触媒メカニズムを解明する.
- Rab GTPasesとGyp1p.を使用したTBCドメインのGAP活動の構造的基礎を調査する.
主な方法:
- TBC-ドメイン-Rab-GTPase-アルミニウムフッ化物複合体のX線結晶学.
- サイト・ディレクテッド・ミュータゲネシスで,触媒の残留物を探知する.
- GTPase活性化タンパク質の活性性を評価するための機能的測定法.
主要な成果:
- 結晶構造は,TBCドメインのGAPが,アルギニン指とグルタミン指の両方を供給していることを明らかにしました.
- TBCドメインのグルタミン指はRab GTPaseと相互作用し,その固有のグルタミンに代わる.
- Rab GTPaseのグルタミン酸は,仮説として移行状態を安定させないが,TBCドメインと相互作用する.
結論:
- TBCドメインのGAPは,GTP水解を加速するために保存された二指触媒機構を使用します.
- このメカニズムは,Ras/RhoファミリーのGAPとの予想された並行とは異なり,ユニークな触媒戦略を強調しています.
- この発見は,Rab GTPasesとそのGAPsによる膜取引の規制に関する新しい洞察を提供します.
関連する概念動画
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
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...
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
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:


