1. Molecular Cell Biology Fifth Edition Chapter 5: Biomembranes and Cell Architecture Copyright © 2004 by W. H. Freeman & Company Harvey Lodish Arnold Berk Paul Matsudaira Chris A. Kaiser Monty Krieger Matthew P. Scott Lawrence Zipursky James Darnell

2. Plasma membrane 1.Affect shape and function 2.Anchor protein to the membrane 3.Modify membrane protein activities 4.Transducing signals to the cytoplasm

5. Lipid Bilayer 1.Impermeable barrier prevent diffusion of water soluble solute 2.Membrane protein mediate transport of specific molecule 3.Maintained by hydrophobic interaction

7. Van der waal interaction between membranes

8. RBC Smooth and flexible

9. Long, slender extension

10. Multiple layers of modified plasma membrane: formed by adjacent glial cells

11. The faces of cellular membrane 1.Internal faces surface orient toward the interior of the compartment 2. External faces the surface presented to the environment

12. Chloroplast in plants

13. 磷酸甘油酯 Acyl group: c16 or c18, 0, 1 or 2 double bond i.e.plasminogen

14. 鞘酯 sphingomyelin glucosylcerobroside choline head 膽鹼

15. Four ring hydrocarbon amphipathic Hydrocarbon chain

16. FRAP: Fluorescent Recovery After Photobleaching

17. Most lipids and proteins are laterally mobile in biomembrane

22. Lipid composition influence physical properties of membrane: 1.Different composition of organs 2.Specialized membrane function i.e. apical surface if intestinal lumen sphingolipids: phosphoglycerides: cholesterol basolateral 0.5 1 1 apical 1 1 1

23. Long saturated fatty acyl chain heat 3. Affects membrane fluity a. short C-H chain are more fluid b. kinks in C-H: less stable Decreased thickness

24. 4. Influence thickness of membrane

25. 5. Local curvature Larger head Smaller head

26. bilayer enriched with PC in the exoplasmic leaflet and with PE in the cytoplasmic face would cause the natural curvature

27. Membrane asymmetry Affects: 1. Enzyme cleavage  phospholipase cleaves phospholipids at exoplasmic sides  cytosolic sides are resist to phospholipase cleavage

28. Cleave phospholipid at cytosolic side

29. 2. Membrane based functions i.e. signal transduction pathway of Cleavage by phospholipase C phosphotidyl inositol PI + Diacylglycerol( DAG) Activation of signal transduction pathway

30. i.e. phosphotidyl serine stimulation of platelate by serum translocate to exoplasmic face activate enzyme for blood clotting

31. Lipid Raft micro domain of cholesterol, sphingolipids and certain membrane protein

32. GM1: glycosphingolipids PLAP: placental alkaline phosphatase

33. TfR: transferrin receptor

34. Three categories of membrane protein 1.Integral membrane protein( transmembrane protein) a. exoplasmic domain cytosolic domain hydrophilic b. Membrane spanning domain: hydrophobic c. glycosylated

35. 2. Lipid anchored membrane protein covalently bound to lipid 3. Peripheral membrane protein bound to membrane by interaction with integral membrane protein

36.   

37. Glycophorin A: a typical single pass transmembrane protein  -helices Binding of Arg or Lys to negatively charged head of phospholipid

38.  -helices: 20-25 hydrophobic amino acids Interact with fattyacyl of lipid by van- der-waals

39. G protein: 7-multipass bacteriorhodopsin retinal

40. Porin  Trimric tramsmembrane protein  Barrel shape subunit with ß- sheet wall and hydrophilic center  aliphatic and aromatic side chain position the protein on the membrane

41. Anchoring of plasma membrane proteins to the bilayer by covalently linked hydrocarbon group 1.anchor by fatty acyl group 2.Anchor by unsaturated fatty acid to cyctein at or near C terminal 3.GPI anchoring lipid anchor on membrane is glycosyl phosphotidyl inositol( GPI)

42. Gly Cys C14 or C16 C15 or C20 Glycosylphosphosphatidylinositol sugar

43. All transmembrane proteins and glycolipids are asymetrically oriented in the bilayer

46. Motility of membrane protein 1.Float freely 2.Immobile 3.Anchored by cytoskeletal protein

47. PH ( pleckstrin homology domain)

48. Interfacial binding surface and mechanism of action of phospholipase A2

49. Effects of external ion concentration on water flowacross the plasma membrane of an animal cells