Plasma Membrane – Phospholipid Bilayer

• Mammalian Red Blood Cells
  • Provided initial evidences that biological membranes consist of lipid bilayers (E. Gorter & F. Grendel, 1925).
  • Since, they do not contain nuclei or internal membranes, thereby becoming a source from which pure plasma membrane can be isolated easily.
  • RBCs’ plasma membrane have been particularly useful as a model for membrane structure studies.

• The plasma membrane of animal cells quantitatively contain-
  • Four major Phospholipids (accounting in total more than half of the lipids in most membranes):
    • Phosphatidylcholine (Phospha-ti-dyl-choline)
    • Phosphatidylethanolamine (Phospha-ti-dyl-ethanol-amine)
    • Phosphatidylserine (Phospha-ti-dyl-serine)
    • Sphingomyelin (Sphingo-myelin)
  • One minor Phospholipid:
    • Phosphatidylinositol (Phospha-ti-dyl-inositol)

• In the outer leaflet of Plasma membrane following phospholipids are present:
  • Phosphatidylcholine
  • Sphingomyelin

• In the inner leaflet of Plasma membrane following phospholipids are present:
  • Phosphatidylserine
  • Phosphatidylethanolamine
  • Phosphatidylinositol

To be continued…