ABSTRACT
Fatty acids in adipocytes can be derived from circulating lipoproteins via lipoprotein lipase, or they can be synthesized via de novo lipogenesis from carbohydrate precursors such as glucose. The functional fatty acid synthase complex is a homodimer of two identical subunits with an apparent molecular mass of approximately 250 kD. The murine fatty acid synthase was identified by differential screening of cDNA libraries derived from liver mRNA of rats that were fasted, or fasted rats then refed a high carbohydrate diet. Fasting in rodents results in decreased glucose conversion into fatty acids; when the animals are subsequently refed a low-fat, high-carbohydrate diet there is a rapid and efficient increase in production of fatty acids and triacylglycerols. Sterol regulatory element-binding proteins are members of the basic-helix-loop-helix-leucine zipper family of transcription factors and regulate enzymes responsible for the synthesis of cholesterol, fatty acids, and triglycerides.
