FABP4 is one of nine known cytosolic fatty acid binding proteins ranging in size from 14-15 kDa containing 127-132 amino acids. Members of this protein family exhibit high-affinity for small lipophilic ligands and were named according to the tissue from which they were initially isolated. Studies suggest that FABPs are involved in the uptake and metabolism of fatty acids, in the maintenance of cellular membrane fatty acid levels, in intracellular trafficking of these substrates, in the modulation of specific enzymes of lipid metabolic pathways, and in the modulation of cell growth and differentiation. FABP family members have highly conserved three dimensional structures and 22-73% amino acid sequence similarity. FABP4 is composed of ten antiparallel β strands that form a barrel. FABP4 is a fat cell specific protein involved in facilitating the bidirectional flux of fatty acids into and out of the adipocyte in response to insulin and epinephrine.
