Ca2+は,脂質の電荷特性を調節することによって,T細胞受容体活性化を調節する
Xiaoshan Shi1, Yunchen Bi, Wei Yang
1State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Nature
|December 4, 2012
まとめ
カルシウムイオン (Ca2+) はアニオン系フォスホリピドに直接結合し,T細胞抗原受容体-CD3複合体 (TCR) 機能を調節する. このCa2+結合は,膜からCD3細胞質ドメインを放出し,チロシンリン酸化とT細胞活性化感性を高めます.
科学分野:
- 分子および細胞生物学
- 免疫学 免疫学とは
- バイオケミストリー バイオケミストリー
背景:
- 陽性タンパク質と脂質の相互作用は,膜タンパク質の機能に不可欠ですが,その調節は依然として十分に理解されていません.
- T細胞抗原受容体-CD3複合体 (TCR) の活性化には,陽性電荷のCD3細胞質ドメイン (CD3 ((CD)) とアニオン系フォスホリピドの相互作用が含まれる.
研究 の 目的:
- カルシウムイオン (Ca2+) がCD3 ((CD)) とアニオン系フォスホリピドの間のイオン相互作用を調節する役割を調査する.
- Ca2+がTCR近辺シグナル伝達とT細胞活性化に影響を与えるメカニズムを解明する.
主な方法:
- バイオケミカルアッセイ
- 生きている細胞の光共振エネルギー転送 (FRET)
- (31) P NMRを含む核磁気共振 (NMR) スペクトロスコーピーは, (31) P NMR を含む.
主要な成果:
- Ca2+濃度の上昇は,CD3 (CD) の膜からの解離を促し,重要なチロシン残基をリン酸化に晒す.
- Ca2+の流入は,T細胞活性化における重要なステップであるCD3チロシンリン酸化を著しく強化する.
- Ca2+は,アニオン系フォスホリピドのリン酸群に直接結合し,それらの負の電荷を中和させ,CD3の解離を促進します.
結論:
- カルシウムイオンは,アニオン系フォスホリピドと相互作用することによって,膜タンパク質機能の直接的調節剤として作用する.
- このCa2+媒介の脂質相互作用は,CD3のリン酸化を拡大し維持し,T細胞の感受性を高め,ポジティブなフィードバックメカニズムを提供します.
- この研究は,直接的なCa2+-脂質相互作用を含むT細胞活性化のための新しい調節経路を明らかにしています.
関連する概念動画
Amplifying Signals via Second Messengers
Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
IP3/DAG Signaling Pathway
Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
Feedback 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...
Calmodulin-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,...
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
T Cell Activation and Clonal Selection
T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...
Naive T cells that have not yet encountered an antigen express two primary CD...


