Studies n Functional Roles of Fatty Acid-Binding Proteins

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We have studied on functional roles of cellular fatty acid-binding proteins (FABPs) in the following aspects.(1) Transfer mechanism of FABP bound-fatty acids to membranes :Using an in vitro fluorescence energy transfer assay, we presented the evidence that H-FABP and L-FABP bound-fatty acids are transferred to membranes through different mechanism. Fatty acids from H-FABP was transferred by collisional interaction, while the rate limiting step from L-FABP was the dissociation rate of fatty acids to aqueous medium.(2) A new FABP (C-FABP) from rat skin :We have purified a new subtype of H-FABP from rat skin and cloned this protein. The deduced amino acid sequence of the cDNA clone comprises residues yielding a molecular mass for the polypeptide of 15 kDa and the primary structure is homologus to H-FABP family proteins. Interestingly, it has six cysteines and two intramolecular disulfide bridges are present. This is the first presentation of disulfide formed protein among FABPs superfamily. Three dimensional structure of this new type of FABP may afford a new sight of functional roles of this protein family in the future.(3) Regulatory mechanism of H-FABP expression in aorta :We have analyzed the H-FABP expression in diabetic rat aorta and provided the evidence that the H-FABP gene in aorta is specifically and uniquely regulated by insulin when compared to the H-FABP expression in heart tissue. Insulin regulated H-FABP expression in aorta may be involved in diabetic complications of blood vessels.(4) Clinical application of I-FABP :Taking the advantage of specific expression of I-FABP limited in intestinal tissue, we have applied the I-FABP as a diagnostic tool. We have showed that the I-FABP is released into the circulation in the acute phase of intestinal ischaemia. Accordingly, the measurement of I-FABP in serum can be used in establishing the diagnosis of ischaemic intestinal diseases.