Forms of cell signaling (A) Hormones produced in endocrine glands are secreted into the bloodstream and can be distributed widely throughout the bod (B) Paracrine signals are released by cells into the extracellular medium in their neighborhood and act locally (C) Neuronal signals are transmitted along axons to remote target cells (D) Contact-dependent signaling requires cells to be in direct membrane-to-membrane contact with each other (especially during development and immune responses
Forms of cell signaling (A) Hormones produced in endocrine glands are secreted into the bloodstream and can be distributed widely throughout the body. (B) Paracrine signals are released by cells into the extracellular medium in their neighborhood and act locally. (C) Neuronal signals are transmitted along axons to remote target cells. (D) Contact-dependent signaling requires cells to be in direct membrane-to-membrane contact with each other. (especially during development and immune responses)
信号分子的接收与灭活 接收:受体( receptor) 灭活:信号分子须在靶细胞膜上或在靶 细胞内起作用后被灭活而将信号消除。 内分泌激素还可在肝脏、血液中被降解,通 过氧化还原、脱氨基、脱羧基方式被清除
信号分子的接收与灭活 • 接收：受体(receptor) • 灭活：信号分子须在靶细胞膜上或在靶 细胞内起作用后被灭活而将信号消除。 – 内分泌激素还可在肝脏、血液中被降解，通 过氧化还原、脱氨基、脱羧基方式被清除
受体( receptor) ·概念 信息分子的接收分子,位于细胞表面或细胞内,化 学本质是蛋白质。 受体的作用 识别外源信息分子(配体 ligand);信号转换。 特点 高度特异性;高亲和力,Kd:108mo/L;可饱和 性;可逆性。 分类: 细胞表面受体(膜受体):分离子通道受体、G蛋 白偶联受体、单次跨膜受体 细胞内受体
受体(receptor) • 概念 – 信息分子的接收分子，位于细胞表面或细胞内，化 学本质是蛋白质。 • 受体的作用 – 识别外源信息分子（配体ligand）;信号转换。 • 特点 – 高度特异性；高亲和力，Kd：10-8 mol/L；可饱和 性；可逆性。 • 分类： – 细胞表面受体（膜受体）：分离子通道受体、G蛋 白偶联受体、单次跨膜受体 – 细胞内受体
CELL-SURFACE RECEPTORS plasma membrane cell-surface receptor Extracellular signaling hydrophilic signaling molecule molecules bind to either cell-surface receptor INTRACELLULAR RECEPTORS or intracellular receptors small hydrophobic signaling molecule carrier protein intracellular receptor
Extracellular signaling molecules bind to either cell-surface receptor or intracellular receptors
(A) ION-CHANNEL-LINKED RECEPTOR Three classes of celll Ions ligand surface receptors (B) G-PROTEIN-LINKED RECEPTOR d G protein activated activated分 enzyme or G protein enzyme or ion channel (C) ENZYME-LINKED RECEPTOR catalytic catalytic domain domain
Three classes of cellsurface receptors