1. MEMBRANE STRUCTURE
LECTURE 4
CHAPTER 10

2. LIPID CLASSIFICATION
PHOSPHOGLYCERIDES
SPHINGOLIPIDS
STEROIDS

3. PHOSPHOGLYCERIDES

4. SPHINGOLIPIDS

5. STEROIDS

6. MEMBRANE BILAYER

7. BILAYER STRUCTURE OF BIOMEMBRANRANES

8. FORMATION OF PURE PHOSPHOLIPID BILAYERS

9. PROPERTIES OF MEMBRANES
HYDROPHOBIC CORE IS AN IMPERMEABLE BARRIER
STABILITY – Van der Waals interaction, and hydrophobic interaction stabilize the fatty acyl groups whereas ionic and hydrogen bonds stabilize the polar head groups
PHOSPHOLIPID BILAYERS SPONTANEOUSLY FORM CLOSED SEALED COMPARTMENTS

10. MEMBRANE BUDDING AND FUSION

11. CYTOSOLIC AND EXOPLASMIC FACES ARE CONSERVED

12. LIPID COMPOSITION IN THE EXOPLASMIC AND CYTOSOLIC FACES OF THE MEMBRANES

13. HOW LIPIDS AFFECT CURVATURE AND THICKNESS OF MEMBRANES

15. PHOSPHOLIPID BILAYER- lateral and rotational movement

16. FRAP EXPERIMENTS

17. FRAP EXPERIMENT (cont’d)

18. MEMBRANE PROTEINS INTEGRAL or TRANS – MEMBRANE PROTEINS
LIPID-ANCHORED MEMBRANE PROTEINS
PERIPHERAL MEMBRANE PROTEINS

19. Integral membrane proteins
Contain membrane spanning α- helices
20-25 hydrophobic uncharged amino acids (3.75 nm)
Segment is perpendicular to the membrane or is at an oblique angle
Amino peptide bonds in the interior of the α-helix
Hydrophobic side chains interact with fatty acyl groups

20. GLYCOPHORIN A – single pass integral membrane protein

21. Multipass Transmembrane Protein

22. Multiple membrane spanning β strands
Porins
Gram-negative bacteris, outer membrane of mitochondria and chloroplasts
Trimers of identical subunits
Each subunit – 16 beta strands that twist to form a barrel-shaped structure
Barrel - Hydrophilic interior and hydrophobic exterior

23. Single subunit of outer membrane Porin from E.coli

24. PERIPHERAL MEMBRANE PROTEINS

25. HOW IS BLOOD GROUP DETERMINED?

27. Mechanism of action of Phospholipase A

28. SOLUBILIZATION OF MEMBRANES

29. BINDING OF FATTY ACID TO THE FATTY –ACID-BINDING PROTEIN

30. PHOSPHOLIPID BIOSYNTHESIS

31. CHOLESTEROL BIOSYNTHESIS

32. MECHANISM OF CHOLESTEROL AND PHOSPHOLIPID TRANSPORT