Showing papers on "Fatty acid-binding protein published in 1987"

A novel acyl-CoA-binding protein from bovine liver. Effect on fatty acid synthesis.

Abstract: Bovine liver was shown to contain a hitherto undescribed medium-chain acyl-CoA-binding protein. The protein co-purifies with fatty-acid-binding proteins, but was, unlike these proteins, unable to bind fatty acids. The protein induced synthesis of medium-chain acyl-CoA esters on incubation with goat mammary-gland fatty acid synthetase. The possible function of the protein is discussed.

Acyl-CoA-binding protein from cow. Binding characteristics and cellular and tissue distribution.

Abstract: Using the tyrosine fluorescence quenching as a criterion for acyl-CoA binding, we have shown that acyl-CoA-binding protein (ACBP) binds acyl-CoA esters with a chain length greater than C8 with equal affinity. The binding studies indicated a binding stoichiometry of 1 mol of acyl-CoA/2 mol of ACBP. The protein was found in liver, adipose tissue, intestinal mucosa, kidney, heart, brain, muscles and mammary gland. The highest concentration was found in liver cytosol and the lowest in muscles and mammary gland. ACBP could not be shown to bind non-esterified fatty acids.

Liver fatty acid binding protein is the mitosis-associated polypeptide target of a carcinogen in rat hepatocytes.

Abstract: Hepatocytes in normal rat liver were found previously to contain a cytoplasmic 14,000-dalton polypeptide (p14) that is associated with mitosis and is the principal early covalent target of activated metabolites of the carcinogen N-2-fluorenylacetamide (2-acetylaminofluorene). The level of immunohistochemically detected p14 was low when growth activity of hepatocytes was low, was markedly elevated during mitosis in normal and regenerating livers, but was very high throughout interphase during proliferation of hyperplastic and malignant hepatocytes induced in rat liver by a carcinogen (N-2-fluorenylacetamide or 3'-methyl-4-dimethylaminoazobenzene). We report here that p14 is the liver fatty acid binding protein. The nucleotide sequence of p14 cDNA clones, isolated by screening a rat liver cDNA library in bacteriophage lambda gt11 using p14 antiserum, was completely identical to part of the sequence reported for liver fatty acid binding protein. Furthermore, the two proteins shared the following properties: size of mRNA, amino acid composition, molecular size according to NaDodSO4 gel electrophoresis, and electrophoretic mobilities in a Triton X-100/acetic acid/urea gel. Their pI values overlapped in 2-dimensional isoelectric focusing/NaDodSO4 gel electrophoresis and showed the same response to delipidation. Either polypeptide reacted with and blocked the antiserum raised against the other polypeptide. The two polypeptides bound oleic acid similarly. Finally, identical elevations of cytoplasmic immunostain were detected specifically in mitotic hepatocytes with either antiserum. The collected findings are suggestive that liver fatty acid binding protein may carry ligands that promote hepatocyte division and may transport certain activated chemical carcinogens.

Cloning and tissue distribution of rat heart fatty acid binding protein mRNA: identical forms in heart and skeletal muscle.

Abstract: A fatty acid binding protein (FABP) has been identified and characterized in rat heart, but the function and regulation of this protein are unclear. In this study the cDNA for rat heart FABP was cloned from a lambda gt11 library. Sequencing of the cDNA showed an open reading frame coding for a protein with 133 amino acids and a calculated size of 14776 daltons. Several differences were found between the sequence determined from the cDNA and that reported previously by protein sequencing techniques. Northern blot analysis using rat heart FABP cDNA as a probe established the presence of an abundant mRNA in rat heart about 0.85 kilobases in length. This mRNA was detected, but was not abundant, in fetal heart tissue. Tissue distribution studies showed a similar mRNA species in red, but not white, skeletal muscle. In general, the mRNA tissue distribution was similar to that of the protein detected by Western immunoblot analysis, suggesting that heart FABP expression may be regulated at the transcriptional level. S1 nuclease mapping studies confirmed that the mRNA hybridized to rat heart FABP cDNA was identical in heart and red skeletal muscle throughout the entire open reading frame. The structural differences between heart FABP and other members of this multigene family may be related to the functional requirements of oxidative muscle for fatty acids as a fuel source.

Studies on fatty acid-binding proteins. The binding properties of rat liver fatty acid-binding protein.

Abstract: 1. The fluorescent fatty acid probe 11-(dansylamino)undecanoic acid binds to rat liver fatty acid-binding protein with a 1:1 stoichiometry. 2. The binding of the fluorescent probe is competitive with long-chain fatty acids. 3. Binding displacement studies were performed with a wide range of fatty acids and other ligands and identified C16 and C18 fatty acids as the preferred fatty acids for rat liver fatty acid-binding protein. No preference was observed for unsaturated fatty acids within this group. 4. Fatty acyl-CoA binds less well than the corresponding fatty acid.

Effect of liver fatty acid binding protein on fatty acid movement between liposomes and rat liver microsomes

Abstract: Although movement of fatty acids between bilayers can occur spontaneously, it has been postulated that intracellular movement is facilitated by a class of proteins named fatty acid binding proteins (FABP). In this study we have incorporated long chain fatty acids into multilamellar liposomes made of phosphatidylcholine, incubated them with rat liver microsomes containing an active acyl-CoA synthetase, and measured formation of acyl-CoA in the absence or presence of FABP purified from rat liver. FABP increased about 2-fold the accumulation of acyl-CoA when liposomes were the fatty acid donor. Using fatty acid incorporated into liposomes made either of egg yolk lecithin or of dipalmitoylphosphatidylcholine, it was found that the temperature dependence of acyl-CoA accumulation in the presence of FABP correlated with both the physical state of phospholipid molecules in the liposomes and the binding of fatty acid to FABP, suggesting that fatty acid must first desorb from the liposomes before FABP can have an effect. An FABP-fatty acid complex incubated with microsomes, in the absence of liposomes, resulted in greater acyl-CoA formation than when liposomes were present, suggesting that desorption of fatty acid from the membrane is rate-limiting in the accumulation of acyl-CoA by this system. Finally, an equilibrium dialysis cell separating liposomes from microsomes on opposite sides of a Nuclepore filter was used to show that liver FABP was required for the movement and activation of fatty acid between the compartments. These studies show that liver FABP interacts with fatty acid that desorbs from phospholipid bilayers, and promotes movement to a membrane-bound enzyme, suggesting that FABP may act intracellularly by increasing net desorption of fatty acid from cell membranes.

Isolation and partial characterization of an amphiphilic 56-kDa fatty acid binding protein from rat renal basolateral membrane.

Abstract: We have identified a 56-kDa fatty acid binding protein in rat renal basolateral membrane and purified it by extraction in nonionic detergent (Triton X-100), followed by gel filtration, DEAE-cellulose chromatography, and affinity chromatography. The purified protein was homogeneous on polyacrylamide gel electrophoresis in the presence of Triton X-100 or SDS. It showed amphiphilic properties on gel filtration, polyacrylamide gel electrophoresis, and oleate-Sepharose 4B chromatography. Its molecular mass was estimated to be 56 kDa by SDS-polyacrylamide gel electrophoresis. The protein showed optimal binding activity at pH 7.5 and 37 degrees C. The apparent Kd for palmitic acid was 0.79 microM. It was immunologically clearly distinct from renal cytosolic fatty acid binding protein.

Placental transfer of non-esterified fatty acids in normal and diabetic pregnancy.

Abstract: The placental transfer of non-esterified fatty acids, predominantly in the direction of mother to fetus, is regulated on a gross scale by the transplacental non-esterified fatty acid gradient. This is maintained by fetal liver lipid uptake and by enhanced lipolysis of circulating triacylglycerol in the pregnant mother. It is also dependent upon maternal placental blood flow, which is reduced in diabetes, upon the fetal umbilical blood flow, upon maternal and fetal albumin concentrations and upon intratrophoblastic fatty acid binding protein, which appears to be altered in diabetes. Circulating maternal triacylglycerols also directly contribute non-esterified fatty acids to the fetus by intraplacental hydrolysis and the hypertriglyceridaemia associated with maternal diabetes, in concert with changes in lipase levels will enhance maternal to fetal lipid flux.

Diffication of high affinity fatty acid receptors in rat myocardial sarcolemmal membranes

Abstract: High affinity receptors for fatty acid were purified from rat cardiac sarcolemmal membrane using gel filtration, DEAE-cellulose chromatography and affinity chromatography The purified protein was homogeneous on polyacrylamide gel electrophoresis with the molecular weight of 60 kDa Binding studies revealed the presence of a single class of high affinity binding sites with an apparent dissociation constant of 10 microM and a maximal binding capacity of 121 pmol/micrograms protein

Fatty acid transport in muscle: the role of fatty acid-binding proteins.

Abstract: Fatty acids form the major fuels for energy production of working heart and of skeletal muscle at rest and during moderate and prolonged exercise. Only a small proportion of fatty acids taken up by muscle is used for anabolic processes such as triacylglycerol and phospholipid synthesis, in contrast to adipose tissue and liver. Blood-borne fatty acids are delivered to muscle bound to albumin or from triacylglycerols in chylomicrons and very-low-density lipoproteins after hydrolysis by lipoprotein lipase. The fatty acids are very effectively extracted by the heart from blood, 40-60% during one transmit time (Opie et al., 1973), although they have to pass many barriers and compartments to reach the myocyte mitochondrion, where their main utilization (oxidation) takes place (Fig. I ) . Endothelial cells lining the intravascular space have to extract and transfer the fatty

Studies on fatty acid binding proteins changes in the concentration of hepatic fatty acid binding protein during development in the rat

Abstract: The concentration of hepatic fatty acid-binding protein was determined in the livers of rats at various stages of development from foetus to young adult. Fatty acid-binding protein concentrations were determined by quantifying the fluorescence enhancement on the binding of the fluorescent probe 11-(dansylamino)-undecanoic acid. A 20-fold increase in the concentration of the protein was observed between the foetus and adult, and this increase was confirmed by immuno-blotting. No other protein in the 14,000-Mr range was observed in the foetus. Possible alternative fatty acid-binding proteins could not be detected in h.p.l.c.-fractionated foetal cytosol by the fluorescence-enhancement method.

Fatty acid binding protein in kidney of normotensive and genetically hypertensive rats.

Abstract: Fatty acid binding protein was purified from renal medulla, and its binding activity and fatty acid composition were determined in spontaneously hypertensive stroke-prone rats (SHRSP). Wistar-Kyoto rats (WKY) were used as controls. Fatty acid binding activity was higher in 5-week-old prehypertensive SHRSP than in control WKY (0.155 +/- 0.006 vs 0.030 +/- 0.001 mol palmitic acid/mol protein). However, in 40-week-old rats, the activity was decreased only in SHRSP with established hypertension (0.035 +/- 0.002 vs 0.028 +/- 0.003 mol palmitic acid/mol protein WKY). Fatty acid compositions were similar among 5-week-old and 40-week-old control WKY and 5-week-old SHRSP (palmitic acid, 24%; stearic acid, 14%; oleic acid, 30%; linoleic acid, 29%; arachidonic acid, 3%), although the total amount of bound long-chain fatty acids was decreased in 5-week-old SHRSP, explaining the high fatty acid binding activity in this preparation. Fatty acid binding protein from 40-week-old SHRSP had an elevated proportion of endogenous arachidonic acid, with other fatty acids being relatively reduced (palmitic acid, 8%; stearic acid, 2%; oleic acid, 4%; linoleic acid, 10%; arachidonic acid, 76%), indicating increased arachidonic acid transport in the cytosol. These results show that genetically hypertensive rats had an alteration in fatty acid transport mediated by fatty acid binding protein; this alteration may be involved in the pathogenesis of hypertension.

Substrates for energy metabolism in the heart: the role of the interstitial compartment.

Abstract: Evidence is presented that, as in cardiomyocytes, vascular endothelial cells use fatty acids, in addition to glucose, as a respiratory fuel. Attention is focused on the cardiac interstitium, lined by vascular cells and cardiomyocytes, which may be enriched with metabolic products from these cells. Also, certain proteins are present in the interstitial fluid (Qi) such as plasma proteins and fatty acid binding protein (FABP). However, the concentration of FABP is so low in Qi that albumin is more important to shuttle long chain fatty acids in the interstitial fluid between cardiomyocytes and the vascular compartment.

Studies on fatty acid-binding proteins. The diurnal variation shown by rat liver fatty acid-binding protein.

Abstract: The concentration of fatty acid-binding protein in rat liver was examined by SDS/polyacrylamide-gel electrophoresis, by Western blotting and by quantifying the fluorescence enhancement achieved on the binding of the fluorescent probe 11-(dansylamino)undecanoic acid. A 2-3-fold increase in the concentration of this protein produced by treatment of rats with the peroxisome proliferator tiadenol was readily detected; however, only a small variation in the concentration of the protein due to a diurnal rhythm was observed. This result contradicts the 7-10-fold variation previously reported for this protein [Hargis, Olson, Clarke & Dempsey (1986) J. Biol. Chem. 261, 1988-1991].

Interaction of Lipid-Lowering Drugs with Fatty Acid-Binding Proteins

Abstract: Concepts regarding the structure and function of the low molecular weight cytosolic fatty acid-binding proteins (FABPs) have expanded considerably over the past decade (for reviews see Bass 1985; Glatz et al. 1985; Ockner 1986). To date, three FABPs, the products of separate genes, have been characterized in some detail regarding their structure, tissue distribution, and regulation Table 1 Comparative Properties of the FABPs Liver FAPB Intestinal FABP Heart FABP Synonyms L-FABP, hFABP, Sterol carrier protein (SCP), Z protein I-FABP, gFABP M-FABP Size (kD) 14.2 15.1 15.0 Tissue expression Liver, small intestine Small intestine Heart and skeletal muscle, testis, ovary, brain, kidney Induction by: Hypolipidemic drugs +++ + 0 Female sex steroid hormones +++ 0 + High fat diet +++ ++ ? . Although many de tails of the function of the FABPs await clarification, a considerable body of evidence supports a broad role for these abundant proteins in the transport, utilization, and cellular economy of long-chain fatty acids, and also in protecting several aspects of cellular function from the potentially injurious effects of fatty acids and their CoA esters. Factors which have been found to modulate FABP concentrations include sex steroid hormones, dietary fat, and peroxisome-proliferating hypolipidemic drugs and phthalic acid esters. This chapter will discuss aspects of our current knowledge regarding the mechanisms and significance of the interaction of the latter group of agents with the FABPs.