Intestinal-type fatty acid-binding protein (I-FABP) FABP is thought to play a role in the intracellular transport of long-chain fatty acids and their acyl-CoA esters. I-FABP is probably involved in triglyceride-rich lipoprotein synthesis. I-FABP binds saturated long-chain fatty acids with a high affinity, but binds with a lower affinity to unsaturated long-chain fatty acids. I-FABP may also help maintain energy homeostasis by functioning as a lipid sensor.