Structure of VLC-PUFA. Free FA form of VLC-PUFA 32:5 n6 (A) and 34:5 n3 (B). Note the polyunsaturated methyl end and the saturated carboxyl terminal ends. (C) A typical phospholipid containing VLC-PUFA esterified to the sn-1position of the glycerol backbone. LC-PUFA, either 22:6 n3 or 20:4 n6, or others can occupy the sn-2 position. The sn-3 position in this scenario is occupied by phosphocholine (This research was originally published in Journal of Lipid Research. Agbaga et al., Retinal very long-chain PUFAs: new insights from studies on ELOVL4 (2010). © The American Society for Biochemistry and Molecular Biology).