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. Author manuscript; available in PMC: 2014 Mar 3.
Published in final edited form as: Annu Rev Nutr. 2013 Mar 22;33:249–269. doi: 10.1146/annurev-nutr-071812-161139

Figure 2.

Figure 2

Pathways for hepatic fatty acid synthesis (FASN). (a) The pathway describes the conversion of dietary glucose to palmitate by de novo lipogenesis; the pathway requires acetyl CoA carboxylase (ACC)-1 and fatty acid synthase. Palmitate (16:0) is a product of de novo lipogenesis but is also derived from the diet. Palmitate is subsequently elongated [fatty acid elongase (Elov)l5 and Elovl6] and desaturated [stearoyl CoA desaturase (SCD)] to form C16–18 saturated and monounsaturated (ω7 and ω9) fatty acids. (b) The essential fatty acids, linoleic acid (18:2, ω6) and α-linolenic acid (18:3, ω3), are derived from the diet. These fatty acids are desaturated [fatty acid desaturases (FADS)1 and FADS2] and elongated (Elovl2 and Elovl5) to form the major C20–22 polyunsaturated fatty acids (PUFAs) appearing in cells, i.e., arachidonic acid (ARA; 20:4, ω6) and docosahexaenoic acid (DHA; 22:6, ω3). DHA production requires peroxisomal β-oxidation (p-βOx). C22 PUFAs are retroconverted to C20 PUFAs by p-βOx.