細胞内アクアポリンの急速なゲーティングとアニオン透過性
1Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Nature
|January 26, 2000
まとめ
ネズミのアクアポリン-6 (AQP6) は,水中輸送だけでなく,異常なイオンチャネル活性を示しています. 腎臓の細胞に含まれるこのタンパク質は,低pHでアニオン伝導性を活性化し,水浸透性を超えた新しい機能を明らかにします.
科学分野:
- バイオフィジックス 生物物理学
- 分子生物学は分子生物学である.
- 腎臓生理学 腎臓生理学
背景:
- アクアポリン (AQP) は,通常,プラズマ膜に含まれる水路タンパク質です.
- しかし,哺乳類のAQP6は,腎上皮質の細胞内小胞に局限しています.
- AQP6の特異的な機能と特性は,依然としてほとんど特徴づけられていない.
研究 の 目的:
- ネズミのアクアポリン-6 (AQP6) のユニークな生体物理的性質と機能的特徴を調査する.
- 腎上皮質におけるAQP6の役割とその潜在的なイオン輸送能力を決定する.
- AQP6.6の活性化メカニズムと選択性を調査する.
主な方法:
- Xenopus laevisの卵細胞におけるAQP6の発現.
- 水とイオン透過性の測定は,オオサイト腫れ検査と電気生理学を用いて行われます.
- 腎臓細胞におけるH+-ATPaseによるコロカライゼーションによるAQP6の局所化の調査.
- 穴の機能と選択性を調べるために,サイト指向型変異性.
主要な成果:
- AQP6は基礎水浸透性が低く,Hg2+処理で大幅に増加します.
- AQP6はHg2+誘導によるイオン伝導性を示しています.
- 低pH (<5.5) は,AQP6.6におけるアニオン伝導性を迅速かつ可逆的に活性化します.
- K72におけるサイト指向変異はイオン選択性を変化させるが,pH活性化を維持する.
結論:
- ネズミのAQP6は,水中輸送に加えて,調節されたアニオンチャネルとして機能する異常な生体物理的特性を有しています.
- AQP6の活動は,pHとHg2+によって調節され,細胞イオンホメオスタシスの役割を示唆しています.
- これらの発見は,イオンチャネルとしてのアクアポリンと,腎臓の生理学におけるそれらの潜在的な役割を探求するための新しい道を開きます.
関連する概念動画
00:26Hydrogen Bonds
109.5K
Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....
109.5K
01:28Electron Transport Chains
85.6K
The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The electron transport chain is a set of proteins found in the inner mitochondrial membrane in eukaryotic cells. Its primary function is to establish a proton gradient that can be used during chemiosmosis to produce ATP and generate electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle.
The ETC is comprised of...
The ETC is comprised of...
85.6K
01:32Chemiosmosis
84.9K
Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives many cellular processes. Oxidative phosphorylation involves two processes— the electron transport chain and chemiosmosis.
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons...
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons...
84.9K
01:45Mitochondrial Membranes
11.7K
A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...
11.7K
01:41The Supercomplexes in the Crista Membrane
2.3K
The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
2.3K
01:25Aquaporins
5.0K
Aquaporins or AQPs are a family of integral membrane proteins whose primary function is to transport water, while some called aquaglyceroporins also transport glycerol. In addition, aquaporins have also been suspected to be involved in transporting volatile substances, such as carbon dioxide and ammonia, across membranes. Such AQPs that act as gas channels are often highly expressed in cells involved in the gaseous exchange, such as red blood cells, epithelial cells, and pulmonary capillaries.
5.0K