棒のGタンパク質アルファサブユニット上のサイトで,エフェクタアクティベーションを媒介する
H M Rarick1, N O Artemyev, H E Hamm
1Department of Physiology and Biophysics, University of Illinois College of Medicine, Chicago 60680.
まとめ
研究者らは,Gタンパク質のアルファサブユニット (トランスデューシンアルファt) の特定の領域を特定し,循環グアノシン3を活性化する.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- セルラー・シグナリング
背景:
- グアニンヌクレオチド結合タンパク質 (Gタンパク質) は,受容体によって活性化される重要な信号トランスデューサーである.
- Gタンパク質は,酵素やイオンチャネルのようなエフェクタータンパク質を,よく理解されていないメカニズムで調節する.
- トランスデューシン (Gt) は,ロッド光受容体における光伝導に不可欠なGタンパク質です.
研究 の 目的:
- Gタンパク質のトランスデューシンアルファサブユニットの特定の部位を特定し,サイクルグアナシン3',5'-モノフォスファートフォスフォディエステラーゼ (cGMP PDE) を活性化させる.
- 受容体活性化とエフェクタ活性化とを結びつけるアルファtサブユニット内の相互作用領域を解明する.
主な方法:
- 機能ドメインをマッピングするためのサイト指向型変異生成とペプチド合成.
- フォスフォディエステラーゼ (PDE) 活性を測定するための生化学的測定法.
主要な成果:
- トランスデューシンアルファt (アルファt) のCOOH末端領域の22アミノ酸ペプチド (残基293-314) は,無傷のアルファtサブユニットの活動を完全に模倣することが判明しました.
- このペプチドは,cGMPフォスフォディエステラーゼ (PDE) を強力に活性化させました.
- 特定された機能部位は,αtサブユニットの受容体活性化ドメインの近くに位置しています.
結論:
- アルファtサブユニットのCOOH末端領域には,cGMP PDEのエフェクター相互作用と活性化のための重要な部位が含まれています.
- この領域はまた,受容体結合に関与しているようで,信号伝達における二重の役割を示唆しています.
- この相互作用部位の解明は,光伝導の分子機構の洞察を提供します.
関連する概念動画
G-protein Coupled Receptors
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
G-protein Coupled Receptors
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
G Protein-coupled Receptors
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
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...
G Protein-coupled Receptors
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
Transducer Mechanism: G Protein–Coupled Receptors
G Protein–Coupled Receptors (GPCRs) are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to various stimuli. GPCRs regulate critical physiological pathways and are excellent drug targets for treating diseases such as diabetes, cancer, obesity, depression, or Alzheimer's. Nearly 35% of approved drugs implement their therapeutic effects by selectively interacting with specific GPCRs.
GPCRs are also called heptahelical, 7TM, or...
GPCRs are also called heptahelical, 7TM, or...


