In 1957, scientist Bennett Clark introduced the protein lecithin theory. According to this theory, a type of phospholipid called lecithin acts as a carrier. On the outer layer of cells, lecithin combines with anions and cations to form ‘ion lecithin complexes’. The ‘ion lecithin complex’ moves from the outer surface of the cell to the inner surface. Under the influence of lecithinase enzyme on the inside of the cell, the compound is broken down to produce choline and phosphotidic acid and cation and anion are released. With the help of ATP, choline and phosphotidic acid move to the outer layer of the cell and combine to form lecithin. Thus anions and cations are absorbed through the cyclic synthesis and breakdown of lecithin.
