Much has been learned about the function of the fat-soluble vitamins in recent years. Their mechanisms are divergent ranging from a role in transcription of DNA or differentiation to a direct enzymatic activation of the gamma-carboxylation of glutamate residues of a preexisting protein. Thus the only resemblance so far among these physiologically active agents is their lipid solubility. However, in general the fat-soluble vitamins play important roles in specialized functions carried out by highly differentiated organisms.
