1 / 29

Cell Signaling

Cell Signaling. How to Get a Message from the outside of the Cell to the inside of the cell. 1. Reception 2. Transduction 3. Response. G-Protein Linked Receptors. G-Protein Linked Receptor Transmembrane Protein (“trans” means “across”, so this protein goes “across” the membrane)

rmunoz
Download Presentation

Cell Signaling

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. Cell Signaling • How to Get a Message from the outside of the Cell to the inside of the cell

  2. 1. Reception 2. Transduction 3. Response

  3. G-Protein Linked Receptors • G-Protein Linked Receptor • Transmembrane Protein (“trans” means “across”, so this protein goes “across” the membrane) • 7 Alpha helices • Outside: Signal molecule binding site. • When a signal molecule (also called a ligand) binds to the signal binding site, this causes the G-Protein Linked Receptor to change shape • e.g. this signal molecule can be epinephrine (adrenaline) • Inside: Changes in G-Protein linked receptor causes another molecule called a G-Protein to change from an inactive to an active state.

  4. G-Protein Linked Receptorsand G-Proteins • G-Protein Linked Receptor is different from a G-Protein (see illustration) • G-Protein Linked Receptor • A transmembrane protein- introduced in the last slide • Detects the signal and changes shape (hence the name “receptor”) • Has “G-Protein” as part of the name because it will also bind with a “G-Protein” inside the cell • G-Protein • Named “G-protein” because GDP is bound to it (GDP is similar to ADP) • Located on the inner membrane of the cell • When GDP is bound to it, it is in its inactive state

  5. G-Protein Linked Receptorsand G-Proteins • Process: • Signal molecule binds to G-Protein Linked Receptor • G-Protein Linked Receptor changes shape • G-Protein Linked Receptor binds to G-Protein (which is inactive) • G-Protein Activation causes GDP to be replaced by GTP • G-Protein with GTP is now in its active form

  6. G-Protein Linked Receptorsand G-Proteins • G-Protein dissociates from the G-Protein Linked Receptor • G-Protein diffuses along the membrane • Binds to an enzyme • This binding activates the enzyme • Results in a cellular response.

  7. CELLULAR RESPONSE AND THE Second Messenger • Adenylyl Cyclase is a common enzyme in these signally pathways • It catalyzes the conversion of ATP to cyclic AMP • Cyclic AMP (cAMP) is known as a second messenger

  8. Second Messenger • Adenylyl Cyclase • Enzyme that catalyzes ATP->cyclic AMP • Cyclic AMP (cAMP) is the second messenger • See structure below

  9. Second Messenger • cAMP activates another protein • Protein Kinase A

  10. Phosphorylation Cascade • Protein Kinase • Enzyme that catalyzes the transfer of phosphate groups from ATP to a protein • 2% of our genome codes for these enzymes!!

  11. Phosphorylation Cascade • Protein Phosphatases • Enzyme that catalyzes the removal of phosphate groups from proteins • Reverse of what protein kinases do.

  12. Epinephrine

  13. G-Protein Linked Receptorsand G-Proteins • G-Protein Inactivation • G-Protein acts as GTPase • Breaks down GTP to GDP • Unbinds from enzyme • Becomes inactive again

  14. Three Step Process 1. Reception 2. Transduction 3. Response

  15. Animations G-Protein Cell Signaling

  16. Is Cell Signaling Important? Earl Sutherland discovered how epinephrine (adrenaline) works to increase glucose to the cells to aid in the “fight or flight response.” -Free Response #1 tonight

  17. G-Protein Linked Receptors • Are G-Protein Linked Receptors really that important?

  18. Tyrosine-Kinase Receptors

  19. Tyrosine-Kinase Receptors

  20. Tyrosine-Kinase Receptors

  21. Tyrosine-Kinase Receptors

  22. Ion Channel Receptors

  23. Ion Channel Receptors

  24. Ion Channel Receptors

  25. Second Messengers • Cyclic AMP • Calcium ions

  26. Calcium Ions

  27. Calcium Ions and IP3

  28. Growth Factors and Stimulation of Transcription

  29. Signal Molecules • G-Protein Linked Receptors • Hormones, neurotransmitters, odors, light sensitive compounds • Involved in bacteria infections • 60% of all medicines today exert their effects by influencing G-protein pathways. • Two Principle Signal Transduction Pathways • Cyclic AMP signal pathway • Phosphatidylinositol (PIP) signal pathway • Tyrosine Kinase Receptors • Growth factors (cell growth, cell reproduction) hormones (insulin), cytokines, can cause cancer

More Related