Diversity of GPCRs

1. G-protein linked receptorsHeny EkowatiJurusan Farmasi FKIKUniversitas Jenderal Soedirman November 2013

4. Diversity of GPCRs

5. IV G12 aactivates chloride channel G13 activates Na+/H+ exchanger pathways activates small G protein Rho family, leading to actincytoskeletal reorganization

7. G-protein-linked receptors; functionally diverse but share a common structure Ligand binding extra-cellular

8. G-protein-linked receptors function through trimeric G-proteins • G-protein-linked receptors • mediate their intracellular actions through target ion channels or enzymes. • pathway always involves activation of one or more • guanine nucleotide-binding regulatory proteins (trimeric G proteins). • trimeric G proteins consist of three protein subunits; alpha, beta and gamma. • The G alpha binds a guanyl nucleotide. • Various types, each specific for a set of serpentine receptors and for a particular downstream target, but they all operate the same way.

10. Receptor, inactive G-proteins, and adenylyl cyclase are within shouting distance in the cell membrane. Ligand binding (1) -conformational change in the receptor -separates TMs. -separation of the TMs may open a crevice for binding to G. Receptor binds to G protein (2)

11. Receptor activation results in • activation of adenylyl cyclase. • -indirect • -stimulates a trimeric G-protein • -trimeric G-proteins dissasemble • when activated. Receptor binds to G-protein induces conformational change (3) GDP is replaced by GTP Ga dissociates from Gbg The binding site for adenylyl cyclase is unmasked. Ga then binds to adenylyl cyclase (4), activating synthesis of cAMP A single hormone/ receptor complex stimulates the production of many molecules of Gsa

12. The binding of the Gas subunit to adenylyl cyclase activates the enzyme to produce many molecules of cAMP. signal amplification Binding of Ga to adenylyl cyclase causes a conformation change in Ga and GTP is hydrolyzed to GDP. This causes Ga to dissociate from adenylyl cyclase and re-bind Gbg

13. Terminating the response • The hormone/receptor complex must be deactivated to return to • the unstimulated state. • -phosphorylation events on the carboxy terminal tail of the receptor • lead to the inactivation of the receptor. • Hydrolysis of GTP leads to inactivation of the trimeric G-protein. • -enhanced by RGS proteins (regulator of G-protein signaling).

14. The trimeric GTP-binding proteins act as molecular switches Functionally couple the G-protein-linked receptors to their target enzymes or ion channels. • GTPases that function as molecular switches • flip between two states: active and inactive. • Inactive; trimer bound to GDP through Ga • Active; Ga bound to GTP • A G-protein which acts to stimulate a target enzyme is called a G stimulatory (Gs). • Gi is inhibitory. two conformation states active inactive

15. Mammalian RGS proteinsactivate the GTPase activities of G-protein alpha subunits RGS proteins are GAPs (GTPase activating proteins). -no effect on the time course of nucleotide binding -but they stimulate the rate of GTP hydrolysis. GTP GDP a GTP hydrolysis a b/g g RGS protein b MODEL: RGS proteins accelerate GTP hydrolysis by preferentially binding to and stabilizing G proteins in their transition state for the hydrolysis reaction.

16. While the beta-adrenergic receptors are functionally coupled to G-stimulatory proteins, the alpha-2 adrenergic receptors are coupled to inhibitory G proteins. Gi can contain the same beta/gamma subunits as Gs, but the alpha subunits are different. Gi inhibits adenylyl cyclase in an indirect manner. Inhibitory G proteins

17. Hormone-induced activation and inhibition of adenylyl cyclase is mediated by G-sa and G-ia

21. Elevation of cytosolic Calcium via the inositol phospholipid signaling pathway

23. GPCR Classes Class A: Rhodopsin like Class B: Secretin like Class C: Metabotropic glutamate / pheromone Class D: Fungal pheromone Class E: cAMP receptors Frizzled/Smoothened family Putative families: * Ocular albinism proteins * Insect odorant receptors * Plant Mlo receptors * Nematode chemoreceptors * Vomeronasal receptors (V1R & V3R) * Taste receptors T2R Orphans: * Putative / unclassified GPCRs non-GPCR families: * Class Z: Archaeal/bacterial/fungal opsins

24. GPCR Classes * Class A Rhodopsin like o Amine o Peptide o Hormone protein o (Rhod)opsin o Olfactory o Prostanoid o Nucleotide-like o Cannabinoid o Platelet activating factor o Gonadotropin-releasing hormone o Thyrotropin-releasing hormone & Secretagogue o Melatonin o Viral o Lysosphingolipid & LPA (EDG) o Leukotriene B4 receptor o Class A Orphan/other * Class B Secretin like o Calcitonin o Corticotropin releasing factor o Gastric inhibitory peptide o Glucagon o Growth hormone-releasing hormone o Parathyroid hormone o PACAP o Secretin o Vasoactive intestinal polypeptide o Diuretic hormone o EMR1 o Latrophilin o Brain-specific angiogenesis inhibitor (BAI) o Methuselah-like proteins (MTH) o Cadherin EGF LAG (CELSR) o Very large G-protein coupled receptor * Class C Metabotropic glutamate / pheromone o Metabotropic glutamate o Calcium-sensing like o Putative pheromone receptors o GABA-B o Orphan GPRC5 o Orphan GPCR6 o Bride of sevenless proteins (BOSS) o Taste receptors (T1R) * Class D Fungal pheromone o Fungal pheromone A-Factor like (STE2,STE3) o Fungal pheromone B like (BAR,BBR,RCB,PRA) o Fungal pheromone M- and P-Factor * Class E cAMP receptors * Frizzled/Smoothened family o frizzled o Smoothened Putative families: * Ocular albinism proteins * Insect odorant receptors * Plant Mlo receptors * Nematode chemoreceptors * Vomeronasal receptors (V1R & V3R) * Taste receptors T2R Orphans: * Putative / unclassified GPCRs non-GPCR families: * Class Z Archaeal/bacterial/fungal opsins

25. GPCR Ligands Rhodopsin family: amine receptors Acetylcholine (muscarinic) Adrenaline Dopamine Histamine Serotonin Octopamine Trace amine Rhodopsin family: peptide receptors Angiotensin Apelin Bombesin Bradykinin C5a anaphylatoxin CC Chemokine CXC Chemokine CX3C Chemokine C Chemokine Cholecystokinin Endothelin fMet-Leu-Phe Galanin Ghrelin KiSS1-derived peptide Melanocortin Motilin Neuromedin U Neuropeptide FF Neuropeptide S Neuropeptide Y Neuropeptide W / neuropeptide B Neurotensin Orexigenic neuropeptide QRFP Opioid Orexin Oxytocin Prokineticin Somatostatin Tachykinin Urotensin II Vasopressin Protease-activated (thrombin) Adrenomedullin (G10D) GPR37 / endothelin B like Chemokine receptor like Melanin-concentrating hormone Follicle stimulating hormone Lutropin-choriogonadotropic hormone Thyrotropin Rhodopsin family: other receptors Rhodopsin Olfactory Prostaglandin Prostacyclin Thromboxane Adenosine Purine / pyrimidine Cannabinoid Platelet activating factor Gonadotropin-releasing hormone Thyrotropin-releasing hormone Melatonin Lysosphingolipid and LPA (EDG) Leukotriene B4 receptor SREB Mas proto-oncogene & Mas-related (MRGs) RDC1 EBV-induced Relaxin LGR like Free fatty acid G protein-coupled bile acid Nicotinic acid GPR GPR45 like Cysteinyl leukotriene Putative / unclassified Class A GPCRs Secretin family Calcitonin Corticotropin releasing factor Gastric inhibitory peptide Glucagon Growth hormone-releasing hormone Parathyroid hormone PACAP Secretin Vasoactive intestinal polypeptide EMR1 Latrophilin Brain-specific angiogenesis inhibitor (BAI) Methuselah-like proteins (MTH) Cadherin EGF LAG (CELSR) Putative / unclassified Class B GPCRs Metabotropic glutamate family Glutamate (metabotropic) Extracellular calcium-sensing GABA-B Pheromone (V2R) Taste receptors (T1R) Orphan GPRC5 Orphan GPCR6 Bride of sevenless proteins (BOSS) Putative / unclassified Class C GPCRs Other families Frizzled / Smoothened family Ocular albinism proteins Vomeronasal receptors (V1R) Taste receptors (T2R) Insect odorant receptors Nematode chemoreceptors Plant Mlo receptors Fungal pheromone cAMP (Dictyostelium) Bacterial rhodopsin

26. (-) Gsα Gi somatostatin G protein-based disease pituitarytumor GHRH Pituitary GHRH Receptor (+) GH secretion cAMP GHRH--Growth-hormone-releasing hormone GH--Growth-hormone

27. Pituitary proliferation and secretion mechanism cAMP GTPase activity Persistent activation of Gs Gs gene mutation Persistent activation of AC Acromegaly or Gigantism

28. Cholera Toxin • enzyme that catalyzes the transfer of ADP ribose from intracellular NAD+ to alpha s. • The ADP ribosylation alters the alpha s so that it can no longer hydrolyze its bound GTP. Thus, alpha s continues to stimulate adenylylcyclase to produce cAMP. • The prolonged production of cAMP in the intestinal epithelial cells causes a large efflux of Na+ and water into the gut, and is responsible for the severe diarrhea that is characteristic of cholera.

29. Effect of cholera toxin Persistent activation of adenylyl cyclase

30. Reseptor Asetilkolin Muskarinik

35. Nestler et al, 2001 Molecular Neuropharmaclogy

36. Reseptor Asetilkolin Muskarinik

38. Reseptor Adrenergik

39. a1 a2 b a1B a1D a2A a2B a2C b1 b2 Receptors and signal transduction in the ANS Adrenergic Receptors a1A b3

40. H O C H C H N H 2 2 H O H O C H C H N H 2 2 O H H O H O C H C H N H 2 O H C H 3 Synthesis of catecholamines T Y R O S I N E C O O H t y r o s i n e h y d r o x y l a s e H O H O C H C H N H D O P A 2 2 C O O H a r o m a t i c L - a m i n o a c i d d e c a r b o x y l a s e H O H O C H D O P A M I N E C H N H 2 2 2 b d o p a m i n e - h y d r o x y l a s e N O R E P I N E P H R I N E p h e n y l e t h a n o l a m i n e - N - m e t h y l t r a n s f e r a s e E P I N E P H R I N E

41. NH 3 COOH Direct acting adrenergic receptor agonists:a1 receptors • Phenylephrine (Neosynephrine) • Methoxamine (Vasoxyl) • Oxymetazoline (Visine) Phospho - lipase C (+) G q PIP 2 H O IP Diacylglycerol 3 C H C H N H C H 2 3 2+ Increase Ca Activate Protein Kinase C O H P h e n y l e p h r i n e Response

42. Direct acting adrenergic receptor agonists:a2 receptors • Clonidine (Catapres) • Methyldopa (Aldomet) • Guanabenz (Wytensin) • Guanfacine (Tenex) • Tizanidine (Zanaflex) NH 3 Adenylate Cyclase (-) G I X K + (+) ATP cAMP COOH Reduce cAMP -Dependent Protein Kinase Activity C l o n i d i n e Response

43. Direct acting adrenergic receptor agonists:b receptors NH 3 Adenylate Cyclase (+) G S ATP cAMP COOH Increase cAMP -Dependent Protein Kinase Activity Response

44. Reseptor Dopamin

45. Nestler et al, 2001 Molecular Neuropharmaclogy,

48. OBAT YANG BEKERJA PADA SISTEM DOPAMINERGIK

50. Reseptor Angiotensin