Showing papers on "Fatty acid-binding protein published in 1983"

Isolation and characterization of the three fractions (DE‐I, DE‐II and DE‐III) of rat‐liver Z‐protein and the complete primary structure of DE‐II

Abstract: Three fractions (DE-I, DE-II and DE-III) of Z-protein (fatty acid binding protein) have been isolated from rat liver cytosol by DEAE-cellulose chromatography and characterized. They had the same molecular weight of 14000 and essentially identical amino acid composition. However, compositions of endogenous fatty acids were found to differ strikingly from one another. Long-chain fatty acids detected in DE-II were palmitic, stearic, oleic, linoleic and arachidonic acids. In contrast to DE-II, DE-III contained mainly arachidonic acid. Molar ratios of endogenous long-chain fatty acids to both DE-II and DE-III were estimated to be around 1.0. Unlike the latter two fractions, DE-I was virtually lipid-free. Analyses of the three fractions by polyacrylamide gel electrophoresis, electrofocusing and DEAE-cellulose chromatography before and after delipidation suggested that the difference between DE-I and DE-II was in part due to fatty acids bound to DE-II. In contrast, DE-III appeared to be somewhat different from these forms in its protein structure, though tryptic peptide mappings of the three fractions did not reveal clear differences among them. Analysis of the primary structure was made on the most abundant fraction, DE-II, to investigate the relationship among the three fractions and to other proteins. The protein was a single chain consisting of 127 amino acid residues and had a mostly acetylated NH2 terminus and a free sulfhydryl group. The complete sequence of Z-protein showed striking homology to cellular retinoid binding proteins and peripheral nerve myelin P2 protein, which indicated the presence of a new family of cellular lipid-binding proteins diverged from a common ancestor. A possible intragenic duplication of Z-protein was also suggested.

Modulation of membrane transport by free fatty acids: inhibition of synaptosomal sodium-dependent amino acid uptake.

Abstract: High-affinity, Na+-dependent synaptosomal amino acid uptake systems are strongly stimulated by proteins which are known to bind free fatty acids. The rate of uptake as well as the overall level of accumulation is increased by such proteins as bovine serum albumin, hepatic fatty acid binding protein, beta-lactoglobulin, and fetuin. Such a stimulation is not observed with proteins which do not bind fatty acids. The transport activity of synaptosomal preparations can be directly correlated with the free fatty acid content of the preparation. Thus, incubation with albumin reduces the free fatty acid content of synaptosomal preparations, suggesting that the stimulatory effects of the proteins are related to their removal of inhibitory fatty acids formed by hydrolysis of membrane lipids during incubation. Inhibition of amino acid uptake is seen with most cis-unsaturated long chain fatty acids while saturated and trans-unsaturated fatty acids have relatively little or no effect. Under conditions in which the ionophore gramicidin D causes an increase of 22Na flux into synaptosomes, oleic acid (50 microM) has no effect on the influx. These data are consistent with the hypothesis proposed earlier by us [Rhoads, D. E., Peterson, N. A., & Raghupathy, E. (1982) Biochemistry 21, 4782] that Na+-dependent amino acid transport carrier proteins reside in a relatively fluid lipid domain in the synaptosomal membrane and that the effects of cis-unsaturated fatty acids are mediated by interactions with such domains.

Self-association of the cardiac fatty acid binding protein. Influence on membrane-bound, fatty acid dependent enzymes.

Abstract: The present study on the fatty acid binding protein, purified from pig heart and studied by three independent techniques (electron spin resonance, circular dichroism, and polyacrylamide gel electrophoresis), suggests that the protein self-aggregates and exists in at least four distinct molecular species. This plurality is demonstrated by the presence of four bands after electrophoretic migration at pH 7.2 and by three transitions of molar ellipticity theta 225 that depend on protein concentration. A mathematical model is formulated to simulate the three transitions and to calculate the concentrations of the four species. The multistates manifest themselves in a complex binding capacity for fatty acid, with two sigmoidal components in the binding curve. A general equation for the curve is formulated, and the characteristic constants are evaluated by a nonlinear least-squares fit. The experimental results and their interpretation in quantitative terms lead to a theoretical evaluation of the importance of this new property of self-aggregation of the protein on the activity of membrane-bound model enzymes which are fatty acid or acyl coenzyme A dependent.

Concomitant increase in hepatic triacylglycerol biosynthesis and cytosolic fatty-acid-binding-protein content after feeding rats with a cholestyramine-containing diet.

Abstract: Cholestyramine feeding of rats increased the rate of palmitate and glycerol incorporation into triacylglycerols of isolated hepatocytes. Concomitantly an increase of fatty-acid binding by hepatic cytosolic proteins was observed, which could be attributed to an elevation of the content of the fatty-acid-binding protein (Mr 12000). The involvement of this protein in cholesterol, bile-acid and triacylglycerol metabolism is discussed.

Oleic acid transfer from microsomes to egg lecithin liposomes: participation of fatty acid binding protein.

Abstract: Oleic acid transfer from microsomes or mitochondria to egg lecithin liposomes was stimulated by fatty acid binding protein. By gel filtration, it could be demonstrated that this protein incorporates oleic acid into liposomes. Fatty acid binding protein transfer activity was higher using microsomes rather than mitochondria, which suggests a selective interaction with different kinds of membranes. Transfer of oleic acid by this soluble protein is greater than that of stearic acid. The results indicate that fatty acid binding protein may participate in the intracellular transport of fatty acids.