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Signal Transduction Pathways

Signal Transduction Pathways. An introduction to Information metabolism Chapter 15 Stryer Biochemistry. Signal Transduction. 1) Membrane receptors transfer information 2) Second messengers relay information from the receptor ligand complex.

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Signal Transduction Pathways

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  1. Signal Transduction Pathways • An introduction to Information metabolism • Chapter 15 Stryer Biochemistry

  2. Signal Transduction • 1) Membrane receptors transfer information • 2) Second messengers relay information from the receptor ligand complex. • 3) Protein phosphorylation is a common means of information transfer

  3. Protein Phosphorylation

  4. 7TM helix receptors • The 7TM helix receptors change conformation upon binding of ligand and activate a G-Protein • Rhodopsin • Β-adrenergenic receptor

  5. Activated G-Protein transmits signal by binding to other proteins G-Protein binding to adenylate cyclase increases the catalytic efficiency of the adenylate cyclase and increases the synthesis of cAMP inside the cell

  6. G-Proteins spontaneously reset themselves Resetting the G-Protein

  7. Receptor resetting

  8. cAMP stimulates the phosphorylation of many target proteins by activating PKA • 1) Glycogen metabolism • 2) Expression of specific genes (CREB) • 3) Synaptic transmission • Serotonin binds to a 7TM helix receptor • cAMP activates PKA • PKA facilitates the closing of K channels by phosphorylation

  9. Hydrolysis of Phosphatidyl inositol Bisphosphate

  10. What are the biochemical effects of IP3? • IP3 causes the rapid release of Ca from intracellular stores (ER, SR) • Causes smooth muscle contration • Glycogen breakdown • Vesicle release

  11. Diacylglycerol activates PKC

  12. Ca2+ Ion is a ubiquitous cytosolic messenger

  13. Ca activates the regulatory protein Calmodulin

  14. Regulation of Calmodulin of Calmodulin kinase

  15. Receptor dimerisation

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