1. Last Class: A. intracellular vesicle traffic 1. ER to golgi 2. endocytosis, exocytosis B. Signaling Transduction 1. Ligand Receptor Interactions, 2. Intracellular signaling molecules, 3. molecule switches: phosphorylation and GTP binding, 4. Signaling integration, 5. complex formation, 6. Signaling amplification, 7. Signaling desensitization

2. Cell Communication Different Receptor Types Ion channel-linked receptors *GPCR signaling *Enzyme linked receptors

3. G Protein Coupled Receptors (GPCR)

4. A G-Protein-Coupled Receptor Or G Protein-linked Receptor 7 transmembrane domains

5. The disassembly of G-Protein upon stimulation Spontaneous deactivation is very fast, in minutes. However, with the help of RGS (regulator of G protein signaling, a GAP for  unit), signals can be shut off even faster

6. The Activation cycle of G- Protein

7. GPCR Signaling: cAMP

8. The visualization of cAMP in nerve cells GPCR->Gs->adenylyl cyclase->cAMP Gi

9. cAMP cycle: GPCR->Gs->adenylyl cyclase->cAMP Cyclic AMP phosphodiesterase breaks down cAMP to 5’-AMP

10. The function of cAMP Targeting PKA (cyclic-AMP-dependent protein kinase A)

11. The Whole Signaling Network related to cAMP

12. Terminology: CRE(cyclic AMP response element); CREB: CRE binding protein; CBP: CREB binding protein

13. GPCR Signaling: Calcium

14. Three Types of Inositol phospholipids PI, PI(4)P, PI(4,5)P2

15. Phospholipase C-  (PLC-  ) Produces DAG (diacylglycerol) and IP3 (inositol 1,4,5- trisphosphate (IP3)) Gq->PLC- 

16. Gq signaling pathways and Calcium

17. Fertilization of an egg by a sperm triggering an increase in cytosolic Calcium 3 major types of calcium channels: 1.Voltage dependent Ca channels on plasma membrane 2.IP3-gated Ca release channels on ER membrane 3.Ryanodine receptor on ER membrane

18. Calcium uptake and deprivation 1. Na/Ca exchanger on plasma membrane, 2. Ca pump on ER membrane, 3. Ca binding molecules, 4. Ca pump on Mitochondia

19. Calcium Frequency encoding signaling strength Local Ca blips, sparks, puffs, reflecting local opening of individual channels in ER, strong local signal induces global activity, the elevated Calcium trigger calcium deprivation system

20. Targeting molecules for Calcium Calcium binding protein Calmodulin

21. Ca 2+ /calmodulin dependent protein kinase (CaM-kinase) Memory function: 1. calmodulin dissociate after 10 sec of low calcium level; 2. remain active after calmodulin dissociation

22. Ca 2+ /calmodulin dependent protein kinase (CaM-kinase) Frequency decoder of Calcium oscillation High frequence, CaM-kinase does not return to basal level before the second wave of activation starts

24. Desensitization of GPCR 1. Inhibitory structural alteration of receptor; 2. receptor internalization; 3. receptor degration GRK (G protein-linked receptor kinase) Arrestin takes to clathrin-coated pits and degradation

25. GPCR Signaling Summary 1. G-protein types 2. cAMP and Calcium signaling pathways 3. desensitization

26. Enzyme-Linked Cell Surface Receptors *Receptor Tyrosine Kinase *Tyrosine kinase associated receptors *Receptor-like tyrosine phosphatase *Receptor serine/threonine kinase Receptor guanylyl cyclase Histidine like associated receptor

27. Receptor Tyrosine Kinases (RTKs)

28. Seven subfamilies of receptor tyrosine kinases

30. Three ways in which signaling proteins can cross-link receptor chains 1. dimer, 2. monomer but brought together by proteoglycan, 3. cluster on membrane

32. The importance of receptor oligomerization

33. The docking of signaling molecules at RTK

34. The binding of SH2-containing intracellular signaling proteins to an activated PDGF receptor

35. The structural view of SH2 domain

36. RTK Signaling: Ras Pathway

37. The regulation of Ras activity, a famous downstream molecule of RTK responsible for cancer development

38. The activation of Ras by RTK signaling

39. The MAP-kinase regulated by Ras

40. RTK Signaling: PI3K Pathway

41. The inositol phospholipids generated by PI3K

42. The recruitment of signaling molecules with PH domains to the plasma membrane during B cell activation One PI3K pathway PH domain: pleckstrin homology domain

43. Another PI3K pathway to regulate cell survival

44. Another PI3K pathway to regulate cell migration PI3K->PIP3->GEF->Rac->Wave->Arp2/3->Actin polymerization Movie: chemotaxis, PI3K and cell migration

45. Intracellular Signaling Pathways activated by RTKs and GPCRs

46. 1.Tyrosine kinase associated receptors Integrins: cell-extracellular matrix adhesion Binding to Src and FAK

47. 1.Receptorlike tyrosine phosphatases Intracellular protein and receptor

48. 1.Receptor Serine/threonine kinase 2.Transforming growth factor (TGF-b) and Smad signaling pathway

50. 1.Protein kinase Summary

51. Enzyme-linked Receptor Signaling Summary 1. receptor types 2. RTK and its signaling: Ras and PI3K 3. Tyrosine kinase associated receptors and Receptor-like tyrosine phosphatase 4. Receptor serine/threonine kinase, TGF-  and Smad

52. Other Signaling Pathways Proteolysis mediated

53. 1.Notch and Delta interaction Lateral inhibition

54. 1.The inhibitory pathway of Notch Proteolysis-mediated

55. 1.The inhibitory pathway of Notch Proteolysis-mediated

56. 1.Wnt Signaling pathway LRP: LDL-receptor-related protein; GSK-3  : glycogen synthase kinase-3  APC: adenomatous polyposis coli;

57. 1.NF-KB pathway

58. Summary 1. GPCR signaling: PKA and Calcium 2. Enzyme-linked Receptor signaling: RTK- >Ras and PI3K 3. Proteolysis-mediated signaling pathways