Cloning of a cDNA encoding rat intestinal fatty acid binding protein

Intestinal fatty acid binding protein mRNA is one of the most abundant mRNA species in the rat small intestinal epithelium. RNA transfer blot analyses disclosed that the mRNA encoding intestinal fatty acid binding protein is ≃900 nucleotides long and not represented in liver RNA. We have identified 564 nucleotides of this mRNA, including 12 nucleotides of the 5' nontranslated region, the coding portion, and 155 nucleotides of the 3' nontranslated domain. The primary translation product encoded by this mRNA contains 132 amino acids and has a M(r) of 15,062. The derived protein sequence was verified by automated sequential Edman degradation of the intact polypeptide isolated from a wheat germ cell-free system. The in vitro product is NH₂-terminally acetylated, a finding that is consistent with its ultimate cytoplasmic destination. Comparison of the amino acid sequence of this protein with liver fatty acid binding protein, a polypeptide specified by the most abundant small intestinal epithelial mRNA, revealed significant homology and similarity in the predicted secondary structures of their NH₂-terminal domains.