1 / 43

Chemical Signaling Between Cells

Chemical Signaling Between Cells. Three general categories of chemical signaling: Cytoplasmic connections between cells Cell-to-cell contact-mediated signaling Free diffusion between cells Distant cells (hormones) Adjacent cells (within interstitial space)

hina
Download Presentation

Chemical Signaling Between Cells

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. Chemical Signaling Between Cells • Three general categories of chemical signaling: • Cytoplasmic connections between cells • Cell-to-cell contact-mediated signaling • Free diffusion between cells • Distant cells (hormones) • Adjacent cells (within interstitial space) • All of latter involves the physical movement of Ligands • That is, Ligand Reception by a Protein • Note that Reception means Molecule-to-Molecule Contact

  2. Chemical Signaling Between Cells

  3. Note how specificity is determined by receptor protein Note dependence on Systemic Circulation (blood/lymph) Long-Distance Diffusion

  4. Local Diffusion e.g., Histamine released from damaged cells in inflammation e.g., Interferon release by viral-infected cells

  5. Note both absence of and lack-of-dependence on Systemic Circulation Local Diffusion

  6. Signal-Transduction Emphasis This chapter’s emphasis is on signals that are released from one cell and allowed to freely diffuse to a second (or more) recipient cell(s) These communications are deliberately initiated, received, and interpreted in order to increase the physiological coordination of the cells in multicellular organisms We will consider in particular those events that follow the reception of chemical signals We will not dwell on the purpose of the signal We also will not dwell on why and how a given cell released a given signal

  7. Three Stages of Signal Transduction • Reception of extracellular signal by cell • Transduction of signal from outside of cell to inside of cell—often multi-stepped • Note not necessarily transduction of ligand • Cellular Response • Response is inititiated and/or occurs entirely within receiving cell

  8. Three Stages of Signal Transduction

  9. 1. Reception 3. Response Three Stages 2a. Transduction 2b. Transduction 2c. Transduction 2d. Transduction Responses usually involve increasing or decreasing some Protein’s Function

  10. Three Stages 1. Reception 2a. Transduction 2b. Transduction 3. Response

  11. Various Responses Note that more than one response can result from the reception of a single ligand

  12. Various Responses

  13. Ligands e.g., nitric oxide e.g., steroid hormones

  14. Intracellular Reception

  15. Extracellular Reception e.g., insulin e.g., epinephrine

  16. Examples of Surface Receptors

  17. G Protein-Linked Receptors

  18. G Protein-Linked Receptors

  19. G Protein-Linked Receptors

  20. G Protein-Linked Receptors

  21. G Protein-Linked Receptors the more ligand binding, the greater the cellular response note how activation is reversible

  22. G Protein-Linked Receptors

  23. G Protein-Linked Receptors

  24. G Protein-Linked Receptors

  25. G Protein-Linked Receptors note how activation is reversible

  26. the more ligand binding, the more K+ in cytoplasm G Protein-Linked Receptors

  27. Protein Kinase & Phosphatase

  28. Tyrosine Kinase Receptors • Note steps involved: • Ligand Reception • Receptor Dimerization • Catalysis (Phosphorylization) • Subsequent Protein Activation • Further Transduction • Response

  29. Tyrosine Kinase Receptors

  30. Ion-Channel Receptors

  31. Note how, via catalysis, one ligand molecule binding gives rise to many new intracellullar molecules Signal Amplification (Cascade)

  32. Phosphorylation Cascade • This reversibility contributes to the dynamic nature of cells: • A protein that is activated by a Protein Kinase in turn is inactivated by a Protein Phosphatase • This means that the effect of signals can’t last forever • For the cellular response to continue, more signal must be received

  33. Phosphorylation Cascade

  34. 100 molecules 102 molecules 104 molecules 104 molecules 105 molecules 106 molecules Epinephrine  Glycogen Breakdown 108 mol Glu-1-Phosphate

  35. Second Messengers

  36. Cyclic AMP (cAMP) 2nd Messenger

  37. Inositol Triphosphate 2nd Messenger

  38. Transduction Pathway Cross-Talk

  39. Specificity of Cell Signaling • Note how same ligand gives rise to different responses • Cells differ in terms of their proteins • Different proteins respond differently to the same environental signals • (note, though, same receptors, different relay) • Different cells behave differently because some, but not all proteins can differ between cell types

  40. Link to Next Presentation

  41. Acknowledgements biology.ucf.edu/courses/bsc2010/08-2010C-02.PPT www.aw.com/bc/ppt/marieb_ap/chap03c.ppt http://zeus.uwindsor.ca/courses/biology/zielinski/204/comm1.ppt http://vaccine.chonbuk.ac.kr/images/cell/Chapter%2015%20Cell.ppt http://faculty.uca.edu/~jmurray/BIOL1440/lec/lec15.ppt \http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/7-signal.ppt http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/9-glycogen.ppt http://homepage.smc.edu/chen_thomas/Bio21/Chpt%2011%20Cell%20Comm.ppt

  42. the more ligand binding, the more K+ in cytoplasm G Protein-Linked Receptors

  43. G Protein-Linked Receptors

More Related