Lipid metabolism in liver of chicks: response to feeding

Fatty-acid synthase is an enzyme complex responsible for the synthesis of the carbon chain of fatty acids. The hepatic activity of this enzyme increases rapidly during a refeeding period following a fast. The activity of fatty-acid synthase in liver of newly hatched chicks rises in parallel with the activities of other lipogenic enzymes at the initiation of feeding. Cycloheximide, an inhibitor of protein synthesis, prevents the feeding-associated rise of other lipogenic enzymes, but not of fatty-acid synthase. Evidence is reviewed that supports the hypothesis that in fasted chicks as well as in unfed, newly hatched chicks, fatty-acid synthase exists in a catalytically less-active form, one that is activated in response to feeding.