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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fatty acid-binding proteins (FABP) are distinct but related gene products which are found in many mammalian cell types. They are generally present in high abundance, and are found in those tissues where free fatty acid (ffa) flux is high. The function(s) of FABP is unknown. Also not known is whether all FABP function similarly in their respective cell types, or whether different FABP have unique functions. The purpose of these studies was to assess whether different members of the FABP family exhibit different structural and functional properties. Two fluorescent analogues of ffa were used to compare the liver (L-FABP) and heart (H-FABP) binding proteins. The propionic acid derivative of diphenylhexatriene (PADPH) was used to examine the physical properties of the ffa binding site on L- and H-FABP, as well as the relative distribution of ffa between FABP and membranes. An anthroyloxy-derivative of palmitic acid, 2AP, was used to monitor the transfer kinetics of ffa from liver or heart FABP to acceptor membranes, using a resonance energy transfer assay. The results demonstrate that the ffa binding sites of both FABP are hydrophobic in nature, although the L-FABP site is more nonpolar than the H-FABP site. Equilibration of PADPH between L-FABP and phosphatidylcholine (PC) bilayers resulted in a molar partition preference of greater than 20: 1, L-FABP PC. Similar studies with H-FABP resulted in a PADPH partition preference of only 3:1, H-FABP: PC. Finally, the transfer of 2AP from H-FABP to acceptor membranes was found to be 50-fold faster than transfer from L-FABP.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem
PMID:A comparison of heart and liver fatty acid-binding proteins: interactions with fatty acids and possible functional differences studied with fluorescent fatty acid analogues. 226 56

Palmitate binding to human erythrocyte ghost membranes has been investigated with ghost preparations suspended in 0.2% albumin solutions. Free unbound palmitate in the extracellular water phase was measured in equilibrium studies using albumin-filled acid loaded ghosts as small semipermeable bags. The apparent dissociation constant of binding to the membrane is 13.5 nM and the binding capacity 19 nmoles per 7.2 x 10(9) cells. The 0 degree C exchange efflux kinetics of palmitate from albumin-filled ghosts is described by a model, which provides estimates of the rate constant of membrane transfer, k3 = 0.024 s-1, independent of the molar ratio of palmitate to albumin (v) and of a mean dissociation rate constant of the palmitate-albumin complex, k1 = 0.0015 s-1 at v 0.2, allowing for a heterogeneity of the palmitate binding to albumin. The values of a third kinetically determined v dependent model constant, Q, the ratio of palmitate bound to the membrane inner surface to palmitate on intracellular albumin, are not different from the Q values obtained by equilibrium experiments. The temperature dependences of k1 and k3 in the interval 0 degrees C to 15 degrees C give activation energies of 96 and 103 kJ/mole, respectively. The 0 degrees C exchange efflux increases about 2 fold in response to a rise of pH from 6 to 9. The results suggest a carrier mediated palmitate flux at low v with a Vmax about 2 pmoles min-1 cm-2 at 0 degrees C pH 7.3.
Mol Cell Biochem
PMID:Fatty acid-binding to erythrocyte ghost membranes and transmembrane movement. 226 61

A fatty acid-binding protein (FABP) from the cytosol of bovine brain was purified by Sephadex G-75 filtration and electrofocusing. The purified protein migrated as a single protein band in 15% polyacrylamide gel electrophoresis with an apparent molecular mass of 14.7 kDa. To ascertain that the purified protein was a FABP, it was submitted to fatty acid-binding tests. Oleic and palmitic acids bound to brain FABP but this was not the case for palmitoyl CoA. By Scatchard analysis the ligand binding values were: Kd = 0.28 microM, Bmax (mol/mol) = 0.6 for oleic acid and Kd = 0.8 microM, Bmax (mol/mol) = 2.1 for palmitic acid. The complete amino acid sequence of the brain FABP was determined and a microheterogeneity was observed. Sequence comparison with other FABPs of known sequence and the observed microheterogeneity demonstrated the presence in brain of several homologous FABPs closely related to heart FABP.
Mol Cell Biochem
PMID:Amino acid sequence and some ligand binding properties of fatty acid-binding protein from bovine brain. 226 68

The unicellular eukaryotic microorganism, Saccharomyces cerevisiae, transformed with a plasmid containing a cDNA fragment encoding bovine heart fatty acid-binding protein (H-FABP) under the control of the inducible yeast GAL10 promoter, expressed FABP during growth on galactose. The maximum level of immunoreactive FABP, identical in size to native protein as judged from SDS-polyacrylamide gel electrophoresis, was reached after approximately 16 hours of induction. Analysis of particulate and soluble subcellular fractions showed that FABP was exclusively associated with the cytosol. FABP expressed in yeast cells was functional as was demonstrated by its capacity to bind 14C-oleic acid in an in vitro assay. Growth of the transformants on galactose as the carbon source was significantly retarded at 37 degrees C. Whereas the fatty acid pattern of total lipids was not altered in transformed cells, desaturation of exogenously added 14C-palmitic acid was significantly reduced both at 30 and 37 degrees C. The lowest percentage of radioactively labeled unsaturated fatty acids was found in the phospholipid fraction.
Mol Cell Biochem
PMID:Expression of a functionally active cardiac fatty acid-binding protein in the yeast, Saccharomyces cerevisiae. 226 71

Peptidylglycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the production of alpha-amidated peptides from their glycine-extended precursors, a posttranslational modification often required for full biological activity. We have previously cloned cDNAs encoding a 108-kDa bovine PAM precursor. To confirm that this cDNA encodes a functional alpha-amidating enzyme and to begin to examine the structural requirements for the biosynthesis of an active PAM enzyme, we constructed expression vectors that placed the cDNA for either the full-sized enzyme or a form truncated at the carboxyl-terminal (and thus lacking the transmembrane domain) under the control of the mouse metallothionein-1 promoter. We used the resultant plasmids to transfect AtT-20 mouse anterior pituitary corticotrope cells and selected stable lines that expressed increased levels of PAM activity. Transfected cells in which expression from the metallothionein promoter had been induced had up to 15-fold higher levels of PAM mRNA and up to 7.5-fold higher levels of PAM activity than wild-type cells. The PAM activity in the transfected cells shared many enzymatic characteristics with PAM-B, a 38-kDa soluble form of PAM purified from bovine neurointermediate pituitary. These included copper- and ascorbate-dependent activity, an alkaline pH optimum for the peptide substrate D-Tyr-Val-Gly, similar affinities for several other synthetic substrates, and comparable apparent size during gel filtration. Compared to extracts of wild-type cells, extracts from transfected cells showed increased production of five different amino acid alpha-amides. These data indicate that a single enzyme can act on a variety of peptide substrates, and that the full structure of the PAM precursor is not necessary during biosynthesis for expression of active PAM enzyme.
Mol Endocrinol 1990 Jan
PMID:Stable expression of full-length and truncated bovine peptidylglycine alpha-amidating monooxygenase complementary DNAs in cultured cells. 232 63

Labeled sialoglycolipids were purified from tissue culture-derived trypomastigotes incubated with [3H]fetuin. Thin layer chromatography of [3H]sialoglycolipids showed three components with the same migration as gangliosides extracted from parasites incubated with [3H]palmitic acid. Neuraminidase treatment or mild acid hydrolysis confirmed the presence of [3H]sialyl residues in sialoglycolipids synthesized after [3H]fetuin incubation. Labeling was not observed when parasites were incubated with free [3H]sialic acid (C7 derivative), suggesting that sialyl residues are directly transferred in vivo to gangliosides, by an enzymatic reaction possibly catalysed by a sialyl transferase (transglycosylase). Sonicated extracts of trypomastigotes incubated with [3H]fetuin catalysed the labeling of endogenous glycoconjugates as well as of bovine brain gangliosides. The transglycosylase activity was found associated with the particulate fraction and could be solubilized with Triton X-100. The specific activity of the sialic acid transglycosylase in epimastigotes is 17% of that found in trypomastigotes. Addition of an excess free sialic acid did not inhibit the reaction, suggesting that transfer does not occur via a pool of free sialic acid.
Mol Biochem Parasitol 1987 Nov
PMID:Direct sialic acid transfer from a protein donor to glycolipids of trypomastigote forms of Trypanosoma cruzi. 244 18

The pathogenic Neisseria have multiple genes encoding proteins that bind monoclonal antibody (MAb) H.8. We previously reported the cloning and sequencing of a meningococcal gene (laz) encoding an H.8 MAb-binding protein with a consensus lipoprotein processing site, an N-terminal domain containing the epitope for H.8 MAb binding, and a C-terminal domain with extensive similarity to the sequences of azurins from other organisms. In the current study, we showed that the product of the cloned gene could be labelled with palmitic acid, that it was subject to globomycin-sensitive processing, and that it was immunologically cross-reactive with azurin from Pseudomonas aeruginosa. All neisserial species tested, both pathogens and commensals, produced a protein recognized by anti-azurin serum. Southern blots with oligonucleotide probes specific for the azurin domain of the gene showed that it was present in a single copy in the chromosome; it was highly conserved in gonococci and meningococci, and less conserved in commensal Neisseria species.
Mol Microbiol 1989 May
PMID:Characterization of the neisserial lipid-modified azurin bearing the H.8 epitope. 247 41

Transport of palmitate from the albumin-palmitate complex in the plasma to inside mitochondria where it undergoes beta-oxidation is a multistep process. Albumin's large size prevents permeation via interendothelial clefts. Palmitate dissociation from albumin in solution is too slow to provide an adequate supply of the unbound palmitate. The discovery that the dissociation occurs upon albumin binding to an endothelial surface receptor resolves the conundrum. Palmitate transport across the luminal surface membrane may be either carrier-mediated or passive. Fatty-acid binding protein inside endothelial and cardiac muscle cells facilitates diffusion through cytosol while maintaining the unbound palmitate concentration at a very low level. Within the interstitium, albumin is again the palmitate carrier. Still controversial is whether or not there is a saturable sarcolemmal transporter or simply passive exchange. Inside the myocyte palmitate is again bound to the fatty acid binding protein which buffers the free palmitate concentration, facilitates diffusion, and may facilitate further intracellular reactions.
Mol Cell Biochem
PMID:Modeling of palmitate transport in the heart. 267 67

Phospholipase A2 (PLA2) inhibits ligand binding to sarcolemmal muscarinic receptors in heart. To determine whether this effect of PLA2 is mediated by membrane accumulation of non-esterified fatty acids (FFA), the effect of selected fatty acids on the binding of 3H-quinuclidinyl benzylate (3H-QNB) to purified canine sarcolemmal membranes before and after PLA2 treatment was examined. Equilibrium 3H-QNB binding was inhibited by 5 min exposure of membrane vesicles to oleic, linoleic or arachidonic acid (IC50 = 6.3 +/- 0.9, 9.9 +/- 1.1, and 6.8 +/- 0.4 microM, respectively); the saturated fatty acids, stearic and palmitic acid (10 microM) had no effect. Scatchard analysis of equilibrium binding isotherms showed that the effect of the unsaturated fatty acids to inhibit 3H-QNB binding reflected a decrease of Bmax and a reduction of the affinity of the remaining receptors. The effect of unsaturated fatty acids was dependent on the mole ratio of fatty acid to membrane phospholipid present (FFA/PL ratio). Washing of fatty acid-treated membranes with bovine serum albumin (BSA) resulted in partial recovery of both maximal binding (Bmax) and affinity. The fatty acid-induced reduction of Bmax was also attenuated if binding was started by simultaneous addition of 3H-QNB and FFA. Similarity of the FFA induced effects on 3H-QNB binding to sarcolemmal muscarinic receptors to those induced by PLA2 suggest that membrane accumulation of unsaturated fatty acids underlies in part the effect of PLA2. Furthermore, modification of the receptor-ligand interaction by changes in the membrane lipid composition may be prevented by ligand occupation of the receptor.
J Mol Cell Cardiol 1989 May
PMID:Inhibition of 3H-quinuclidinyl benzylate binding to cardiac muscarinic receptor by long chain fatty acids can be attenuated by ligand occupation of the receptor. 277 5

Cis-unsaturated fatty acids, but not saturated fatty acids, inhibited phospholipase A2 activity (PLA2) in vitro, and may function as endogenous suppressors of lipolysis. To probe the possible role of lipid peroxidation in the regulation of myocardial lipid catabolism, a neutral-active and Ca2+-dependent PLA2 was extracted from rat heart and was partially purified by sulfopropyl cation exchange chromatography. Myocardial PLA2 activity was inhibited in a dose-dependent manner by oleic, linoleic, linolenic, and arachidonic acids; the IC50 for arachidonic acid was approx 65 microM. Palmitic acid was not inhibitory. When arachidonic acid was incubated at 37 degrees C, exposed to air, there was a time- and pH-dependent peroxidation of the arachidonic acid as monitored by turbidity, thiobarbituric acid reactivity, and thin layer chromatography. Peroxidation was increased as the pH was lowered from 7.5 to 4.5, and was accompanied by a decrease in PLA2 inhibitory potency. Thus, arachidonate incubated for 24 hours at pH's 4.5, 6.0 and 7.5 lost 84%, 32%, and 20% respectively, of its inhibitory potency. Therefore, in vitro acidosis promotes the oxidation of cis-unsaturated fatty acids and relieves their inhibitory or suppressive activity toward PLA2s. Increased lipid peroxidation of unesterified unsaturated fatty acids during acidosis may therefore promote lipolysis observed during myocardial ischemia and reperfusion injury.
Mol Cell Biochem
PMID:Fatty acid oxidation and myocardial phospholipase A2 activity. 277 34


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