LIgand-activated cell-surface receptors lon-channel receptors: acetylcholine G-protein-coupled receptors: epinephrine, glucagon, serotonin tyrosine kinase-linked receptors: EGF, PDGF, interferons. insulin tyrosine phosphatase receptors: CD45 serine/therinine kinase receptors: TGFB, BMP guanylate cyclase receptor: atrial naturetic factor Most cells have 10,000-30,000 molecules of receptors on their cell surface
The functions of receptors Receptor-mediated endocytosis >Signal transduction 1. The activation of receptor make for the cascades 2. The desensitization of receptor make for close down of the cascades, 3. The down-regulation of receptor make for the depressed reaction, o Different kinds of intracellular signaling proteins along a signaling pathway from a surface receptor to the nucleus
❖The functions of receptors: ➢Receptor-mediated endocytosis; ➢Signal transduction: 1. The activation of receptor make for the cascades; 2. The desensitization of receptor make for close down of the cascades; 3. The down-regulation of receptor make for the depressed reaction; ❖Different kinds of intracellular signaling proteins along a signaling pathway from a surface receptor to the nucleus
extracellular signal molecule receptor protoin latent gene regulatory protein sna membrane Relay proteins simply pass the message to the next CYTOSOL signaling component in the chain scaffold protein elay proteins Messenger proteins carry the signal from one part to another(from cytosol to nucle us). Adaptor proteins link one signa ling proteins to another Amplifier proteins, (enzymes or ion channels) amplifier and transducer protein signaling cascade. Transducer proteins convert the signal into a dfferent form integrator proten Bifurcation(分峻 proteins spread the signal from one signaling pathway to another. Integrator proteins receive signals from two or more signaling pathways and integrate ying a signal onward 分 nuclear envelope Latent gene regulatory proteins are activated at the cell surface by activated receptors and then migrate to the nucleus to stimulate target protean gene trascription. activated gene
Relay proteins simply pass the message to the next signaling component in the chain. Messenger proteins carry the signal from one part to another(from cytosol to nucleus). Adaptor proteins link one signaling proteins to another Amplifier proteins, (enzymes or ion channels) signaling cascade. Transducer proteins convert the signal into a dfferent form. Bifurcation(分歧) proteins spread the signal from one signaling pathway to another. Integrator proteins receive signals from two or more signaling pathways and integrate them before relaying a signal onward. Latent gene regulatory proteins are activated at the cell surface by activated receptors and then migrate to the nucleus to stimulate gene trascription
A) PREFORMED SIGNALING COMPLEX ON SCAFFOLD nactive receptor signal molecule activated receptor ☆ Most activated cell surface receptors relay CYTOSOL inactive 1 activated signals via small molecules intracellular scaffold signaling protein 1 signaling protein 1(second messengers) and a protei inactive ctivated intracellular signaling protein 2 a goaling protoin 2 network of intracellular inactive activated intracellular intracellular signaling proteins signaling protein 3 signaling protein 3 ☆ Two types of downstream signals intracellular signaling (B) ASSEMBLY OF SIGNALING COMPLEX FOLLOWING RECEPTOR ACTIVATION complexes, enhance the inactive receptor signal molecule speed,efficiency, and specificity of the response. activate intracellular signalin pto nactive intracellular signaling proteins
❖Most activated cellsurface receptors relay signals via small molecules (second messengers) and a network of intracellular signaling proteins. ❖Two types of intracellular signaling complexes, enhance the speed,efficiency,and specificity of the response
s Interactions between intracellular signaling proteins are mediated by modular binding domains signal molecule inositol receptor phospholipid TB SH2(P CYTOSOL signaling protein 1 P kinase domain Ph domain. signaling protein 2 Pleckstrin:血小板、白细胞C激 kinase domain SH2 酶底物同源域 adaptor protein B cell activation SH3 signaling protein 3 RELAYS SIGNAL DOWNSTREAM BINDING DOMAIN MOTIF RECOGNIZED PH= Pleckstrin homology domain phosphorylated inositol phospholipid PTB= phosphotyrosine-binding domain SH2= Src homology 2 domain ⊙Y= phosphotyrosine SH3- Src homology 3 domain IPPPL -proline-rich motif
❖Interactions between intracellular signaling proteins are mediated by modular binding domains PH domain: Pleckstrin:血小板、白细胞C激 酶底物同源域 B cell activation