Question

The erythrocyte membrane consists of different phospholipids that are asymmetrically distributed across the membrane. Explain the different lipid composition of the inner and outer leaflets of the erythrocyte membrane. Which leaflet would you expect to be the most permeable to Na+ or Cl– ions? Explain your answer?

Answer 1

Plasma membrane is a lipid bilayer. It is made up of two layers, inner leaflet and outer leaflet. It is selectively permeable in nature because it regulates the transportation of molecules across the cell surface. The composition of inner leaflet and outer leaflet is different.

Outer leaflet - phosphatidylcholine, sphingomyelin, glycolipids

Inner leaflet - phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol

More number of transporters will be present on the outer leaflet in comparison to the inner leaflet and therefore outer leaflet will be more permeable to sodium ions and chloride ions. It is because outer leaflet will be less specific for the transportation of molecules in comparison to the inner leaflet which will be more specific.

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