Fatty acid-binding protein

About: Fatty acid-binding protein is a research topic. Over the lifetime, 1721 publications have been published within this topic receiving 81530 citations. The topic is also known as: FABP.

Fatty acid interactions with native and mutant fatty acid binding proteins.

Abstract: The interactions of long chain fatty acids (FA) with wild type (WT) fatty acid binding proteins (FABP) and engineered FABP mutants have been monitored to determine the equilibrium binding constants as well as the rate constants for binding and dissociation. These measurements have been done using the fluorescent probes, ADIFAB and ADIFAB2, that allow the determination of the free fatty acid (FFA) concentration in the reaction of FA with proteins and membranes. The results of these studies indicate that for WT proteins from adipocyte, heart, intestine, and liver, Kd values are in the nM range and affinities decrease with increasing aqueous solubility of the FA. Binding affinities for heart and liver are generally greater than those for adipocyte and intestine. Moreover, measurements of the rate constants indicate that binding equilibrium at 37°C is achieved within seconds for all FA and FABPs. These results, together with the level of serum (unbound) FFA, suggests a buffering action of FABPs that helps to maintain the intracellular concentration of FFA so that the flux of FFA between serum and cells occurs down a concentration gradient. Measurements of the temperature dependence of binding reveal that the free energy is predominately enthalpic and that the enthalpy of the reaction results from FA-FABP interactions within the binding cavity. The nature of these interactions were investigated by determining the thermodynamics of binding to engineered point mutants of the intestinal FABP. These measurements showed that binding affinities did not report accurately the changes in protein-FA interactions because changes in the binding entropy and enthalpy tend to compensate. For example, an alanine substitution for arginine 106 yields a 30 fold increase in binding affinity, because the loss in enthalpy due to the elimination of the favorable interaction between the FA carboxylate and Arg106, is more than compensated for by an increase in entropy. Thus understanding the effects of amino acid replacements on FA-FABP interactions requires measurements of enthalpy and entropy, in addition to affinity. (Mol Cell Biochem 192: 77–85, 1999)

Rabbit heart fatty acid-binding protein. Isolation, characterization, and application of a monoclonal antibody.

Abstract: A fatty acid-binding protein (FABP) was purified from rabbit heart and characterized with respect to size, isoelectric point, and tissue distribution. This protein was found in red muscle, diaphragm, and aorta, as well as in the heart. Amino acid composition of rabbit heart FABP differed only slightly from the human and rat proteins. Rabbit heart FABP was shown to bind two molecules of fatty acid. A monoclonal antibody was developed and used to demonstrate the feasibility of a one-step purification with affinity chromatography. Cross-reactivity was found between the human protein and the rabbit antibody, and an immunoassay was developed to human heart FABP. Levels of human heart FABP in the plasma of patients with acute myocardial infarction were significantly elevated (83 +/- 9 micrograms/ml) compared with patients with pulmonary edema (52 +/- 7 micrograms/ml) and normal volunteers (28 +/- 5 micrograms/ml; p less than 0.05, mean +/- SEM).

Cell-type-specific regulation of genes involved in testicular lipid metabolism: fatty acid-binding proteins, diacylglycerol acyltransferases, and perilipin 2.

Abstract: Male germ cell differentiation entails the synthesis and remodeling of membrane polar lipids and the formation of triacylglycerols (TAGs). This requires fatty acid-binding proteins (FABPs) for intracellular fatty acid traffic, a diacylglycerol acyltransferase (DGAT) to catalyze the final step of TAG biosynthesis, and a TAG storage mode. We examined the expression of genes encoding five members of the FABP family and two DGAT proteins, as well as the lipid droplet protein perilipin 2 (PLIN2), during mouse testis development and in specific cells from seminiferous epithelium. Fabp5 expression was distinctive of Sertoli cells and consequently was higher in prepubertal than in adult testis. The expression of Fabp3 increased in testis during postnatal development, associated with the functional differentiation of interstitial cells, but was low in germ cells. Fabp9, together with Fabp12, was prominently expressed in the latter. Their transcripts increased from spermatocytes to spermatids and, interestingly, were highest in spermatid-derived residual bodies (RB). Both Sertoli and germ cells, which produce neutral lipids and store them in lipid droplets, expressed Plin2. Yet, while Dgat1 was detected in Sertoli cells, Dgat2 accumulated in germ cells with a similar pattern of expression as Fabp9. These results correlated with polyunsaturated fatty acid-rich TAG levels also increasing with mouse germ cell differentiation highest in RB, connecting DGAT2 with the biosynthesis of such TAGs. The age- and germ cell type-associated increases in Fabp9, Dgat2, and Plin2 levels are thus functionally related in the last stages of germ cell differentiation.

Fatty acid binding proteins and mammary‐derived growth inhibitor

Abstract: The multigene superfamily of intracellular lipid binding proteins in mammals comprises up to now 13 different types of 14-15kDa proteins. whose foremost high-affinity ligands are long-chain fatty acids, retinoids and bile acids, respectively. The phylogenetically related proteins of highly conserved tertiary structure are encoded by genes. that are canonically structured into four exons and three introns. In addition, these genes are characterized by promoter regions with responsive elements common to many genes encoding lipid-metabolizing enzymes, that interact with nuclear receptors activated by peroxisome proliferators or fatty acids. On the basis of interactions of fatty acids -actually macronutrients - with the ligand activated nuclear receptors and with the fatty acid binding proteins (FABPs) the regulation of FABP-expression and the functions of the various FABP-types in cellular lipid homeostasis, signal transduction and growth regulation will be reviewed.

Intestinal fatty acid binding protein: folding of fluorescein-modified proteins.

Abstract: The rat intestinal fatty acid binding protein is an almost all beta-sheet protein that encloses a large interior cavity into which the fatty acid ligand binds. The protein contains neither cysteine nor proline. In a previous report, six site-directed mutants were obtained, each having a single cysteine residue [Jiang, N., & Frieden, C., (1993) Biochemistry 32, 11015-11021] either in a turn or pointed into the cavity. In this report, each mutant has been unfolded in denaturant and modified with 5-iodoacetamido-fluorescein to introduce a large, bulky, and fluorescent group into the protein at a known position. In all cases, fluorescence changes indicated that the modified protein refolded, and circular dichroism measurements suggested that the refolded protein appeared to be mostly beta-sheet. Denaturation curves suggest that for two mutants intermediate structures exist at denaturant concentrations well below the midpoint of the unfolding curve. For each modified, folded protein, one- and two-dimensional 1H NMR spectra were accumulated and compared to the unmodified and wild-type proteins. While the spectra for the modified proteins showed a number of changes in chemical shifts, they were also consistent with folded proteins on the basis of the degree of chemical shift dispersion. Of the six modified mutant proteins, two appear to have the fluorescein group located in the cavity, but only one of these did not bind fatty acid. The remaining modified proteins are capable of ligand binding.(ABSTRACT TRUNCATED AT 250 WORDS)