Modifications of Proteins—Glycosolation, Lipidation, Phosphorylation

CHEMICAL MODIFICATIONS OF PROTEINS— GLYCOSOLATION, LIPIDATION, PHOSPHORYLATION 

The function of these additional chemical groups is not well understood. In some cases, they serve as molecular switches, activating the protein only when it is needed. Glycosolation is the most prevalent modification in eukaryotic cells, and it appears to increase the protein s solubility and decrease its susceptibility to proteolytic attack. Lipid attachment to proteins is usually seen when the protein s function requires its presence near a membrane surface within the cell. The polar portion of the lipid is attached covalently to the protein while the hydrophobic tail of the lipid is imbedded in the membrane. The lipid group thus serves as an anchor for the soluble protein. Finally, many of the enzymes 

---