Fatty acid transport protein complex. Molecular model of the complex formed by a fatty-acid binding protein (FABP, blue and yellow) with the fatty acid lauric acid (dodecanoic acid) and a potassium ion (purple). The molecule of lauric acid is at upper centre (green [carbon] and red [oxygen]). The surrounding structure is the FABP, with its secondary structure (blue alpha helices and yellow beta sheets). The fatty-acid-binding proteins (FABPs) are transport proteins for fatty acids and other lipophilic substances such as eicosanoids and retinoids. FABPs are essential in seed formation; this one is from the thale cress (Arabidopsis thaliana).