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Seven-Transmembrane Receptor Signaling

Seven-Transmembrane Receptor Signaling. Heterotrimeric G-proteins & Second Messenger Pathways. 7TM Receptor Interacting with Trimeric G-Protein. Canonical 7TM Signaling Pathway - I. Activated receptor Binds heterotrimeric G-protein (G  ) specific ones for specific receptors

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Seven-Transmembrane Receptor Signaling

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  1. Seven-Transmembrane Receptor Signaling Heterotrimeric G-proteins & Second Messenger Pathways

  2. 7TM Receptor Interacting with Trimeric G-Protein

  3. Canonical 7TM Signaling Pathway - I • Activated receptor • Binds heterotrimeric G-protein (G) • specific ones for specific receptors • Activated receptor is GEF • exchanges GDP for GTP on G • G dissociates from G • G activates/inhibits downstream transducers • adenylyl cyclases • phosphodiesterases • phospholipases • G activates/inhibits downstream transducers • inhibition of kinases that inactivate 7TM receptors

  4. Canonical 7TM Signaling Pathway – II • Adenylyl cyclase • synthesis if cAMP ([cAMP] increase 100X) • cAMP activates protein kinase A (PKA) • PKA (S/T kinase) • regulated by RII (regulatory II) subunit • RII subunit is binds cAMP or PKA catalytic subunit • deregulation by cAMP allows PKA to phosphorylate numerous substrates • PKA can enter nucleus and phosphorylate many transcriptions factors • activates and inhibits

  5. Canonical 7TM Signaling Pathway – III • Turning off the signals • RGS – regulators of G-protein signaling) • GAPs for G subunits that stimulate GTP hydrolysis • hydrolysis allows Greassociation • downstream kinasesphosphorylate 7TMreceptors • blocks further G proteinstimulation

  6. Cyclic Nucleotides

  7. Adenylyl Cyclase • Converts ATP to cAMP • Stimulated by Gs • Inhibited by Gi

  8. Removal of Cyclic Nucleotides • Phosphodiesterases cut 3'-O-P bond to generate 5' nucleoside monophosphates • cAMP AMP • cGMP GMP Phosphodiesterase

  9. Cyclic Nucleotide Activated Kinases • Protein kinases • PKA • cAMP • cAMP binds to RII subunit • releases PKA from autoinhibition • PKG • cGMP

  10. -Andrenergic Receptors

  11. Formation of Lipid 2nd Messengers

  12. Lipid Second Messengers & Targets

  13. Lipid 2nd Messenger Activated Protein Kinases • Protein Kinase C Family

  14. Phosphoinositol Second Messenger Signaling

  15. Ca2+ Second Messenger Signaling

  16. Odorant Receptors

  17. Photoreceptors

  18. Eicosanoids

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