1 / 59

Signal transmission and signal transduction

Signal transmission and signal transduction. XIA Qiang , MD & PhD Department of Physiology Room 518, Block C, Research Building School of Medicine, Zijingang Campus Email: xiaqiang@zju.edu.cn Tel: 88206417 (Undergraduate school), 88208252 (Medical school). OUTLINE.

smarin
Download Presentation

Signal transmission and signal transduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Signal transmission and signal transduction XIA Qiang, MD & PhD Department of Physiology Room 518, Block C, Research Building School of Medicine, Zijingang Campus Email: xiaqiang@zju.edu.cn Tel: 88206417 (Undergraduate school), 88208252 (Medical school)

  2. OUTLINE • Intercellular signal transmission • Chemical transmission • Electrical transmission • Signal transduction pathway • Pathways initiated by intracellular receptors • Pathways initiated by plasma membrane receptors

  3. Intercellular signal transmission • Chemical transmission • Chemical signals • Neurotransmitters:

  4. Intercellular signal transmission • Chemical transmission • Chemical signals • Neurotransmitters: • Humoral factors: • Hormones • Cytokines • Bioactivators

  5. Intercellular signal transmission • Chemical transmission • Chemical signals • Neurotransmitters: • Humoral factors: • Gas: NO, CO, etc.

  6. Intercellular signal transmission • Chemical transmission • Chemical signals • Receptors • Membrane receptors • Intracellular receptors

  7. Receptors on the surface of a cell are typically proteins that span the membrane

  8. Only Cell A has the matching receptors for this chemical messenger, so it is the only one that responds Cells B & C lack the matching receptors Therefore are not directly affected by the signal

  9. Intercellular signal transmission • Electrical transmission Gap junction

  10. Cardiac Muscle Low Magnification View The intercalated disk is made of several types of intercellular junctions. The gap junction provides a low resistance pathway for the action potential to spread from cell to cell

  11. Signal transduction pathway • Pathways initiated by intracellular receptors • Pathways initiated by plasma membrane receptors

  12. This hydrophobic signal requires a carrier protein while in the plasma … … but at the target cell the signal moves easily through the membrane and binds to its receptor

  13. Signal transduction pathway • Pathways initiated by intracellular receptors • Pathways initiated by plasma membrane receptors (transmembrane signal transduction)

  14. Transmembrane signal transduction

  15. Transmembrane signal transduction • Mediated by G protein-linked receptor • Mediated by enzyme-linked receptor • Mediated by ion channel

  16. Binding of ligands to membrane-spanning receptors activates diverse response mechanisms

  17. Transmembrane signal transduction • Mediated by G protein-linked receptor • Mediated by enzyme-linked receptor • Mediated by ion channel

  18. The Nobel Prize in Physiology or Medicine 1994 • "G-proteins and the role of these proteins in signal transduction in cells" Alfred G. Gilman Martin Rodbell

  19. The Discovery of G Proteins Normal Lymphoma Cell Mutated Lymphoma Cell

  20. Activation and Inactivation of the G Protein

  21. G-protein-coupled Receptors

  22. G protein effector   Second messenger   Protein kinase Signaling molecules involved

  23. Main signaling pathways (1) cAMP-PKA pathway (2) IP3-Ca2+ pathway (3) DG-PKC pathway (4) G protein-ion channel pathway

  24. cAMP-PKA pathway Gs, Gi

  25. The cyclic AMP second messenger system

  26. Adenylyl cyclase forms cAMP, a “second messenger” that activates enzymes used in cellular responses The phosphodiesterase enzymes “terminate” the second messenger cAMP

  27. The cAMP system rapidly amplifies the response capacity of cells: here, one “first messenger” led to the formation of one million product molecules

  28. Cells can respond via the cAMP pathways using a diversity of cAMP-dependent enzymes, channels, organelles, contractile filaments, ion pumps, and changes in gene expression

  29. (2) IP3-Ca2+ pathway: Gq (3) DG-PKC pathway: Gq DAG: diacylglycerol IP3: inositol 1,4,5-trisphosphate PIP2: phospholipid phosphatidylinositol 4,5-bisphosphate

  30. This receptor-G-protein complex is linked to and activates phospholipase C, leading to an increase in IP3 and DAG, which work together to activate enzymes and to increase intracellular calcium levels

  31. Click here to play the Membrane Bound Receptors, G Proteins, and Calcium Channels Flash Animation

  32. (4) G protein-ion channel pathway

  33. Binding of the ligand to the receptor alters the receptor’s shape, which activates an associated G-protein, which then activates effector proteins, i.e., enzyme functions or ion channels

  34. The calcium-calmodulin system is similar to some of the cAMP pathways, because it results in the activation of protein kinases that can phosphorylate key proteins required for cellular responses

  35. The “arachidonic acid cascade” is activated in inflammation responses; “cox inhibitors” block cyclooxygenase

  36. Not all responses to hydrophilic signals are immediate: Increases in gene expression can occur, and the resulting proteins can increase the target cells’ response

  37. Eicosanoid: A lipid mediator of inflammation derived from the 20-carbon atom arachidonic acid (20 in Greek is "eicosa") or a similar fatty acid. The eicosanoids include the prostaglandins, prostacyclin, thromboxane, and leukotrienes.

  38. Transmembrane signal transduction • Mediated by G protein-linked receptor • Mediated by enzyme-linked receptor • Mediated by ion channel

  39. Binding of the ligand to the receptor alters the receptor’s shape, which activates its enzyme function, phosphorylating an intracellular protein

  40. (1) Tyrosine Kinase Receptor

  41. Insulin receptor

  42. Growth factor receptor

  43. Mitogen-activated protein kinase (MAPK) pathway • PTK: protein tyrosine kinase • Ras: G protein. It consists of an a subunit, b subunit, and g subunit • MAPKKK: MAPK kinasekinase • MAPKK: MAPK kinase • MKP: MAPK phosphatases • TF: tissue factor

  44. (2) Receptor-associated tyrosine kinase JAK stands for Janus kinase or Just Another Kinase JAK2=Tyrosine protein kinase 2

  45. Binding of the ligand to the receptor alters the receptor’s shape, which activates an associated enzyme function, phosphorylating an intracellular protein

More Related