MgtE Mg2+トランスポーターの結晶構造
Motoyuki Hattori1, Yoshiki Tanaka, Shuya Fukai
1Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.
Nature
|August 19, 2007
まとめ
MgtEのようなマグネシウムトランスポーターは,細胞マグネシウムホメオスタシスに不可欠です. 構造的な研究は,MgtEが細胞内Mg2+レベルを感知することによって,マグネシウムイオン輸送を調節する方法を示しています.
科学分野:
- バイオケミストリー バイオケミストリー
- 構造生物学 構造生物学とは
- 分子生理学 分子生理学
背景:
- マグネシウムイオン (Mg2+) は,多くの生理学的プロセスに不可欠です.
- Mg2+トランスポーターは,Mg2+の吸収を促進しますが,そのメカニズム,特に水素化されたMg2+の脱水は不明です.
- Mg2+トランスポーターのMgtEファミリーは広く存在し,マグネシウムホメオスタシスに関与するヒトの同類体があります.
研究 の 目的:
- MgtE Mg2+トランスポーター機能の構造的基礎を解明する.
- 完全な長さのThermus thermophilus MgtE構造とそのMg2+に依存する形状の変化を特徴付けるために.
主な方法:
- X線結晶学を用いて,全長MgtEとその細胞領域の構造を決定した.
- 構造は3.5 Å,2.3 Å,3.9 Åの解像度で,Mg2+の存在と不在で解けられました.
主要な成果:
- MgtEトランスポーターは,トランスメブランと細胞塩基ドメインを持つホモディメリックアーキテクチャを示しています.
- トランスメブラン領域を通る孔は,Asp 432.2を含む潜在的なMg2+結合部位を示しています.
- サイトゾールドメインへのMg2+結合は,結合ヘリクスの構成変化を誘導し,孔を開くことを潜在的に調節します.
結論:
- Mg2+がMgtEの細胞塩基領域に結合すると,Mg2+の流動を調節するようです.
- これは,MgtEが細胞内Mg2+濃度を感知して輸送を制御するホメオスタシスメカニズムを示唆しています.
- 毛孔ゲーティング (イオンチャネル対二次活性輸送) の正確なメカニズムについては,さらなる調査が必要です.
関連する概念動画
02:42Ionic Crystal Structures
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
01:12Mechanically-gated Ion Channels
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
01:21G-Protein Gated Ion Channels
GPCRs are primarily responsible for our sense of smell, taste, and vision. The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory organs,...
Sensory organs,...
01:12Mechanically-gated Ion Channels
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...