Lysosomal lipid chaperone which binds to a wide range of unsaturated fatty acids, including high affinity binding to oleic acid and oleoylethanolamide, to transport them into the nucleus (PubMed:31292465, PubMed:25554789). As part of a lysosome-to-nucleus retrograde lipid signaling pathway, translocates into the nucleus where it activates the transcription of genes promoting longevity and activation of mitochondrial beta oxidation (PubMed:30713071, PubMed:25554789). Monomer. Intestine. Belongs to the calycin superfamily. Fatty-acid binding protein (FABP) family.