2. Dr.S.Chakravarty, MD

3. List the various types of receptors in the cells Differentiate the features of water and fat soluble hormones List the various second messengers involved in signal transduction Describe the G protein and its coupled receptor in detail Differentiate intrinsic and extrinsic tyrosine kinase mediated pathways of signal transduction Describe the mechanism of insulin release and the structure of insulin receptor

7. Receptors for various hormones Intracellular (transcription factors) – type 1 hormones Cell surface – type 2 hormones

8. EffectDaysMinutes to hours

10. Growth factors!

13. Primary receptor for most of type 2 hormones. Link receptors to second messengers Serpentine -7 channel transmembrane receptor Coupled to G proteins. 4 types of G proteins – G s, G i, G q and G 12 3 heterotrimers of G proteins – αβγ subunits.

16. G- α β γ ATP C -AMP Protein Kinase A Enzyme P P CREB P P CRE GDP (Inactive) GDP (Inactive) Adenylate Cyclase Cell membrane Cytosol Plasma G – protein coupled Receptor  cAMP mediated pathway GTP (active) GTP (active) cAMP response element binding protein cAMP response element Second messenger is cAMP

17. c-AMP pathway cont.. PKA is also known as cAMP-dependent protein kinase

19. c-AMP 5’-AMP ActiveInactive H2OH2O Phosphodiesterase (-) Methyl Xanthines (Caffeine, Theophylline, Theobromine )

21. Classes and Functions of Selected G Proteins 1 Class or TypeStimulusEffectorEffect GsGs α s α Olf Glucagon, α -adrenergics Odorant Adenylyl cyclase Cardiac Ca 2+, Cl –, and Na + channels Adenylyl cyclase Glyconeogenesis, lipolysis, glycogenolysis Olfaction GiGi α i-1,2,3 α 0 α t Acetylcholine, α 2 -adrenergics M 2 cholinergics Opioids, endorphins Light Adenylyl cyclase Potassium channels Calcium channels Potassium channels cGMP phosphodiesterase Slowed heart rate Neuronal electrical activity Vision GqGq α q α 11 M 1 cholinergics α 1 -Adrenergics Phospholipase C-β1 Phospholipase C-β2 Decreased Muscle contraction and decreased Blood pressure G 12 α 12 ThrombinRhoCell shape changes

23. Serine / threonine phosphorylation: Protein kinase A and C and G attach phosphate groups to hydroxyl groups of serine and threonine – to phosphorylate proteins

24. Calcium is required for : Skeletal muscle contraction Blood clotting Secretion of various hormones and enzymes Membrane excitability Enzymatic activity.

26. G- q β γ Phospholipase C PIP-2 DAG IP-3 Protein kinase C Endoplasmic Reticulum Ca 2+ Enzyme, Contractile Proteins Enzyme, Contractile Proteins Enzyme, Contractile Proteins Enzyme, Contractile Proteins G – protein coupled Receptor --- PIP-2 mediated pathway GTP GDP (Inactive) GDP (Inactive)

27. IMP

28. Enzymes and Proteins Regulated by Calcium or Calmodulin Adenylyl cyclase Ca 2+ -dependent protein kinases Ca 2+ -Mg 2+ -ATPase Ca 2+ -phospholipid-dependent protein kinase Cyclic nucleotide phosphodiesterase Some cytoskeletal proteins Some ion channels (eg, L-type calcium channels) Nitric oxide synthase Phosphorylase kinase Phosphoprotein phosphatase 2B Some receptors (eg, NMDA-type glutamate receptor) Harper 29 th

30. Enzyme P Protein kinase Phosphatases ATP ADP H2O Glucagon Epinephrine Insulin P

31. ADP-ribosyltransferase ADP-ribosyltransferases

32. Cholera toxin – causes ADP ribosylation of G αS & subunit and inhibits intrinsic GTPase activity – prolonged action of adenylate cyclase – watery diarrhea Pertussis toxin – causes ADP ribosylation of G α i-2 and prevents dissociation of α i-2 from βγ subunit.G αs activity in such cells unopposed. Usmle!

33. Diphtheria toxin – causes ADP ribosylation of eEF-2 and inhibits protein synthesis by inhibiting translocation of ribosomes Tetrodotoxin – is a neurotoxin which acts on fast sodium channels in the neuronal membrane and inhibit action potential in the neurons.( pufferfish, porcupinefish, ocean sunfish or mola, and triggerfish, ) Usmle!

34. membrane bound Guanyl cyclase GTP C-GMP GTP Protein kinase G Vasodilation (smooth muscle) NO ANF Soluble Guanyl cyclase Soluble Guanyl cyclase 5’- GMP Phosphodiesterase Anti anginal Drugs +

35. Membrane bound Guanyl cyclase – Atrial natriuretic peptide (ANP). Soluble Guanyl cyclase – nitrates, nitroprusside, NO. Sildenafil (Viagra) – phosphodiesterase V inhibitor Remember :-Theophylline, caffeine – phosphodiesterase inhibitors.

36. Sodium nitroprusside – arterial and venodilator Nitroglycerine – veins Hydralazine – arterial Artery – decreased TPR and BP Vein – decreased preload and cardiac output

37. Receptor tyrosine kinase Insulin and growth factors

38. Tyrosine kinases – phosphorylate proteins at hydroxyl groups of tyrosine amino acid With intrinsic tyrosine kinase activity Insulin receptor IGF -1 EGF, PDGF, FGF MAP kinase  RAS protein Without intrinsic tyrosine kinase GH, Prolactin Erythropoietin Cytokines Janus kinase  STAT (signal transducers and activators of transcription)

39. I Beta subunit Alpha subunit GLU T-4 G G G G I Phosphorylation of Insulin Receptor substrates GLU T-4 G G G PHOSPHORYLATION OF TYROSINE RESIDUES DIFFERENT PATHWAYS

41. Serine phosphorylation instead of tyrosine phosphorylation of insulin receptor– mediated by inflammatory mediators like TNF- alpha, interleukins, free fatty acids etc.

42. Insulin dependent translocation Well fed state/abundant glucose in blood PI-3 kinase pathway Exercise induced translocation: During exercise – no insulin AMPK pathway

43. Pathway G-protein Enzyme Second messenger Protein kinase C-AMPGs or GiAdenylate cyclase C-AMPPK –A C-GMPSingle channelGuanyl cyclaseC-GMPPK - G PIP-2GqPhospholipase CIP-3, Ca2+ and DAG PK - C Insulin and GFsIRS and SH2 domains Tyrosine kinase Protein phosphatase

44. SRE Steroid receptor HSP 90 Steroid hormone ( Cortisol) In the absence of the steroid hormone cortisol, Glucocorticoid receptor resides in the cytosol complexed with several chaperone proteins including Hsp90

45. Foye’s Medicinal Chemistry, 7 th Edition by Lemke

46. p50 p65 Ikb Cytokines, TNF a, free radicals, viruses IKKcomplex P + Nucleus Ubiquitin proteosome pathway Steroids inhibit this pathway and act as potent anti-inflammatory agents (Inhibitor of Κb) IκB kinase

47. DBD – DNA BINDING DOMAIN LBD – LIGAND BINDING DOMAIN HINGE REGION - Highly variable region that provides flexibility to the receptor, so it can assume different DNA-binding conformations AF-1 transactivation domain referred

48. CREB binding protein & p300 coactivator

49. Histone acetyl transferase activity Recruitment of RNA pol II to the promoter region of the gene of interest Helps in transcription and translation of proteins.

50. MCQ 1

51. MCQ 2

52. The phosphorylase kinase-associated regulatory protein identified by the letter A in Figure 3-4 is a calcium-binding protein. Which of the following proteins represents this regulatory subunit? MCQ 3

53. Thank you