Phosphatidylthreonine (PT)

Although phosphatidylserine is distributed widely among animals, plants and microorganisms, it is usually less than 10% of the total phospholipids, the greatest concentration being in myelin from brain tissue. However, it may comprise 10 to 20 mol% of the total phospholipid in the plasma membrane and endoplasmic reticulum of the cell. In yeasts, such as S. cerivisiae, it is a minor component of most cellular organelles other than the plasma membrane, where it can amount to more than 30% of the total lipids. In most bacteria, it is a minor membrane lipid, although it is important as an intermediate in phosphatidylethanolamine biosynthesis. The 1-octadecanoyl-2-docosahexaenoyl molecular species, which may be especially important in brain tissue, is illustrated here. Phosphatidylserine is an acidic (anionic) phospholipid with three ionizable groups, i.e. the phosphate moiety, the amino group and the carboxyl function.