第十一章细胞信号转导与疾病.ppt

Communications Between Cells Local Diffusion Long-Distance Diffusion （A）细胞内受体蛋白作用模型;（B）几种胞内受体蛋白超家族成员 A protein kinase transfers the terminal phosphate of ATP to a hydroxyl group on a protein. A protein phosphatase catalyzes removal of the Pi by hydrolysis. Scaffolding proteins help organize MAPKs PKA activation by cAMP Signal Amplification (Cascade) Epinephrine ? Glycogen Breakdown Activation of Ras-RAF-MAPK Activation of MAPK cascade The docking of signaling molecules at RTK The binding of SH2-containing intracellular signaling proteins to an activated PDGF receptor Receptor Serine/threonine kinase Transforming growth factor (TGF-b) and Smad signaling pathway 3. Receptors associated with tyrosine kinases outside-in flow STAT: signal transducers and activators of transcription JAK: janus kinase Ligand-gated ion channels are protein pores that open or close in response to a chemical signal. This allows or blocks ion flow, such as Na+ or Ca2+. Binding by a ligand to the extracellular side changes the protein’s shape and opens the channel. Ion flow changes the concentration inside the cell. When the ligand dissociates, the channel closes. 4. Ion-channel receptors outside-in flow Hormone (testosterone) EXTRACELLULAR FLUID Receptor protein DNA mRNA NUCLEUS CYTOPLASM Plasma membrane Hormone- receptor complex New protein Figure 11.6 1 The steroid hormone testosterone passes through the plasma membrane. The bound protein stimulates the transcription of the gene into mRNA. 4 The mRNA is translated into a specific protein. 5 Testosterone binds to a receptor protein in the cytoplasm, activating it. 2 The hormone- receptor complex enters the nucleus and binds to specific genes. 3 5. Intracellular and nuclear receptors outside-in flow Testosterone, like other hormones, travels through the blood and enters cells throughout the body. In the cytosol, they bind and activate receptor proteins. These activated proteins enter the nucleus and turn on genes tha