Chapter 12 Cell Signaling Part 2a

• 1. Audio file recorded on previouslyto cover for missed class on Wednesday October 24, 2012

2. Receptors and Signal Transduction Defining receptors and signal transduction Examples of receptor types Receptor characteristics Measuring receptor activity 3. G-protein coupled receptors 4. G-protein coupled receptors Receptor tertiary structure is conserved Serpentine Receptor interacts with G-protein astransducer protein Effector enzyme generally produces 2ndmessengers 5. Cell activity canchange in responseto external signals1. Signal release2. Signal binding3. Transmission of information across a membrane4. Protein-protein transmission5. Second messenger synthesis6. Second messenger initiates signaling pathway7. Activated signaling pathway8. Activated target protein9. Changes in cell activity 6. Generic three dimensional structureof a receptor that acts through a G-protein: Serpentine receptorOrange G-proteinbinding domainRed-phosphorylationdomain 7. G-protein coupled receptors(serpentine receptors) producesecond messengersExamples of second messengers 8. Epinephrine signaling is a classic exampleof a G-protein mediated pathway Receptor: -adrenergic Transducer: G protein Effector:Adenylate cyclase Second messenger target: Protein kinase A Physiological targets: Sugar and lipid metabolism Respiration and heart rate 9. What is epinephrine? 10. -adrenergic pathway: Epinephrine signaling: (Adrenaline) 11. Heterotrimer G-proteins cycle throughactive and inactive forms 12. -adrenergic pathway: Epinephrine signaling: (Adrenaline) 13. Binding of cAMPto Protein kinaseA leads to releaseof regulatorysubunits activitythe kinase 14. Crystal structure of Protein kinase A 15. Holding these complexes in the membrane requires A kinaseanchoring proteins 16. Heterotrimer G-proteins cycle throughactive and inactive formsGilman and RodbellNobel Prize inPhysiology and Medicine,1994 17. Additional protein factors regulatethe activity of G proteins 18. G proteins can be locked in active states by toxins 19. -adrenergic pathway: Epinephrine signaling: (Adrenaline) 20. Binding of cAMPto Protein kinaseA leads to releaseof regulatorysubunits activitythe kinase 21. -adrenergic pathway: Epinephrine signaling: (Adrenaline) 22. How can we demonstratethat cAMP releases the catalytic subunits in vivo? GFP and other fluorescent proteins combined with FRET2008 Nobel Prizein Chemistry forGFPMarty ChalfieOsamu ShimomuraRoger Tsien 23. Wavelengths of fluorescent protein emission 24. Fluorescence resonance energy transfer (FRET) 25. Demonstrationof release ofcatalyticsubunits bycAMP binding 26. FRET can also be used to measurePKA activity in a living cell 27. Binding of cAMPto Protein kinaseA leads to releaseof regulatorysubunits activitythe kinase