関連する実験動画
Updated: Aug 12, 2026
10:24
Cytosolic Calcium Measurements in Renal Epithelial Cells by Flow Cytometry
Published on: October 28, 2014
サルコプラズマの網膜にはアデニンヌクレオチドで活性化されたカルシウムチャネルが含まれています
Nature
|August 1, 1985
まとめ
アデニンヌクレオチドによって活性化された骨格筋のカルシウム放出チャネルは,サルコプラズマ網膜から迅速なカルシウム放出を促進します. これらのチャネルは,二価イオンに対する大きな伝導性と選択性を示す.
科学分野:
- 筋肉生理学 筋肉生理学
- 分子生物学は分子生物学である.
- イオンチャンネル研究 イオンチャンネル研究
背景:
- 骨格筋における刺激-収縮結合は,サルコプラズマ網膜 (SR) から急速なカルシウム流出を必要とします.
- アデニンヌクレオチドは,SRからのカルシウム流出を刺激することが知られており,カルシウム放出チャネルの役割を示唆しています.
研究 の 目的:
- 骨格筋のサルコプラズマ網膜から核酸で活性化されたカルシウム放出チャネルの生体物理的特性を特徴づける.
主な方法:
- "重い"SR膜の浄化と,SRタンパク質を平らな脂質二重層に挿入する.
- チャンネル活動とイオン輸送を分析するためのシングルチャネル記録.
- タンパク質の挿入のための融合技術を使用し,導電性と透過性の測定を通じてチャネル特性を特徴付けました.
主要な成果:
- 浄化されたSR膜から単一のカルシウム放出チャネルを特定し記録しました.
- チャンネルはアデニンヌクレオチドによって活性化され,ルテニウムによって遮断された.
- 大量の導電性 (50 mM Ba2+で170 pS) が観察され,二価イオン (P(Ba) /P(Cs) = 11.4 に対する有意な選択性がある.
結論:
- 特定されたチャネルは,核酸で活性化されたチャネルを通じた被動的拡散機構と一致する急速なカルシウム流出を媒介する.
- 大きな導電性とカチオン選択性は,骨格筋のカルシウム放出チャネルに関する重要な生体物理学的な洞察を提供します.
関連する概念動画
01:26Cross-bridge Cycle
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
01:34ATP Driven Pumps II: P-type Pumps
The P-type pumps are a large family of integral membrane transporter ATPases. They are divided into five major types based on substrate specificity, from I to V.
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:29Relaxation of Skeletal Muscles
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
01:25Smooth Muscle Contraction
Smooth muscle contraction is a complex process vital for various bodily functions, from maintaining blood vessel tension to facilitating the movement of food through the digestive tract. Unlike striated muscles, smooth muscle contraction begins more slowly and lasts longer.
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...