イオンチャネルの根元をたどる
1Howard Hughes Medical Institute, Department of Physiology, San Francisco, California.
Cell
|May 29, 1992
まとめ
最近の発見は,イオンチャネルが祖先の酵素から進化したと示唆しており,現在,いくつかのタンパク質は,チャネルと酵素の両方の機能を現しています. この二重機能は,それらの進化的起源と機械的結合に関する疑問を提起する.
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
- 進化生物学の進化生物学について
背景:
- イオンチャネルの5つのクラス (電圧ゲート,Ca2+活性化K+,サイクルヌクレオチドゲートカチオン,フォスホイノシチド媒介Ca2+エントリー,および植物K+チャネル) の間のシーケンスの類似性は,共通の祖先を示唆しています.
- ATP結合カセット (ABC) スーパーファミリーのメンバーは,以前はトランスポーターまたは酵素として知られ,現在はイオンチャネルとして機能することが認められています.
研究 の 目的:
- イオンチャネルの進化的起源を探求する.
- イオンチャネル機能と酵素機能の両方を有するタンパク質のメカニズム的影響を調査する.
主な方法:
- イオンチャネルファミリーの比較シーケンス分析.
- ABC超家族タンパク質とイオンチャネル機能に関する既存の文献のレビュー.
主要な成果:
- 構造的な類似性は,最も最近のイオンチャネル超ファミリーのメンバーが,動物と植物の分岐に先立つ先祖のチャネルに似ていることを示唆しています.
- いくつかのABCタンパク質は,二重イオンチャネルと酵素活性を示し,従来の分類に異議を唱える.
結論:
- イオンチャネルと酵素は,異なる,重複しないタンパク質グループではないかもしれません.
- タンパク質の二重機能は,酵素活性 (例えば,ATP水解) とチャネル調節の間の結合メカニズムを理解し,その逆も理解する必要があります.
- チャネル活動と酵素活動とのクロスレギュレーションは,細胞機能統合の新たな可能性を提供します.
関連する概念動画
Ion Channels
The movement of ions like sodium, potassium, and calcium into and out of the cell is essential to maintain the electrochemical gradient in living cells. The ion channels—a class of membrane transport proteins—help maintain this ionic gradient for the smooth functioning of physiological activities such as maintaining cell size and volume, conducting nerve impulses, and gas and nutrient exchange.
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
Non-gated Ion Channels
Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Ligand-gated Ion Channels
Ligand-gated ion channels are transmembrane proteins with a channel for ions to pass through and a binding site for a ligand. The channel opens only when a ligand attaches to the binding site.
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
Non-gated Ion Channels
Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Ligand-gated Ion Channels
Ligand-gated ion channels are transmembrane proteins with a channel for ions to pass through and a binding site for a ligand. The channel opens only when a ligand attaches to the binding site.
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
Voltage-gated Ion Channels
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...


