991 resultados para Heparan sulfate proteoglycans


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"U.S. AEC Contract AT(49-1)-545."

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Mode of access: Internet.

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The literature relative to the chemistry and technology of magnesium sulfate is presented. The literature titles and chemical abstracts numbers are given, together with a subject index.

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Mode of access: Internet.

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Sulfate plays an essential role during growth, development, bone/cartilage formation, and cellular metabolism. In this study, we have isolated the human sulfate anion transporter cDNA (hsat-1; SCL26A1) and gene (SAT1), determined its protein function in Xenopus oocytes and characterized SAT1 promoter activity in mammalian renal cell lines. hsat-1 encodes a protein of 75 kDa, with 12 putative transmembrane domains, that induces sulfate, chloride, and oxalate transport in Xenopus oocytes. hsat-1 mRNA is expressed most abundantly in the kidney and liver, with lower levels in the pancreas, testis, brain, small intestine, colon, and lung. The SAT1 gene is comprised of four exons stretching 6 kb in length, with an alternative splice site formed from an optional exon. SAT1 5' flanking region led to promoter activity in renal OK and LLC-PK1 cells. Using SAT1 5' flanking region truncations, the first 135 bp was shown to be sufficient for basal promoter activity. Mutation of the activator protein-1 (AP-1) site at position 252 in the SAT1 promoter led to loss of transcriptional activity, suggesting its requirement for SAT1 basal expression. This study represents the first functional characterization of the human SAT1 gene and protein encoded by the anion transporter hsat-1.

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Sulfate (SO42-) is required for bone/cartilage formation and cellular metabolism. sat-1 is a SO42- anion transporter expressed on basolateral membranes of renal proximal tubules, and is suggested to play an important role in maintaining SO42- homeostasis. As a first step towards studying its tissue-specific expression, hormonal regulation, and in preparation for the generation of knockout mice, we have cloned and characterized the mouse sat-1 cDNA (msat-1), gene (sat1; Slc26a1) and promoter region. msat-1 encodes a 704 amino acid protein (75.4 kDa) with 12 putative transmembrane domains that induce SO42- (also oxalate and chloride) transport in Xenopus oocytes. msat-1 mRNA was expressed in kidney, liver, cecum, calvaria, brain, heart, and skeletal muscle. Two distinct transcripts were expressed in kidney and liver due to alternative utilization of the first intron, corresponding to an internal portion of the 5'-untranslated region. The Sa1 gene (similar to6 kb) consists of 4 exons. Its promoter is similar to52% G+C rich and contains a number of well-characterized cis-acting elements, including sequences resembling hormone responsive elements T3REs and VDREs. We demonstrate that Sat1 promoter driven basal transcription in OK cells was stimulated by tri-iodothyronine. Site-directed mutagenesis identified an imperfect T3RE at -454-bp in the Sat1 promoter to be responsible for this activity. This study represents the first characterization of the structure and regulation of the Sat1 gene encoding a SO42-/chloride/oxalate anion transporter.

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In variable charge soils, anion retention and accumulation through adsorption at exchange sites is a competitive process. The objectives of this study in the wet tropics of far north Queensland were to investigate (i) whether the pre-existing high sulphate in variable charge soils had any impact on the retention of chloride and nitrate, derived mostly from the applied fertilizer; and (ii) whether chloride competed with nitrate during the adsorption processes. Soil cores up to 12.5 m depth were taken from seven sites, representing four soil types, in the Johnstone River Catchment. Six of these sites had been under sugarcane (Saccharum officinarum-S) cultivation for at least 50 years and one was an undisturbed rainforest. The cores were segmented at 1.0 m depth increments, and subsamples were analysed for nitrate-N, cation (CEC)- and anion-exchange capacities (AEC), pH, exchangeable cations (Ca, Mg, K, Na), soil organic C (SOC), electrical conductivity (EC), sulphate-S, and chloride. Sulphate-S load in 1-12 m depth under cropping ranged from 9.4 to 73.9 t ha(-1) (mean= 40 t ha(-1)) compared with 74.4 t ha(-1) in the rainforest. Chloride load under cropping ranged from 1.5 to 9.6 t ha(-1) (mean= 4.9 t ha(-1)) compared to 0.9 t ha(-1) in the rainforest, and the nitrate-N load from 113 to 2760 kg ha(-1) (mean = 910 kg ha(-1)) under cropping compared to 12 kg ha(-1) in the rainforest. Regardless of the soil type, the total chloride or nitrate-N input in fertilisers was 7.5 t ha(-1), during the last 50 years. Sulphate-S distribution in soil profiles decreased with depth at >2 m, whereas bulges of chloride or nitrate-N were observed at depths >2 m. This suggests that chloride or nitrate adsorption and retention increased with decreasing sulphate dominance. Abrupt decreases in equivalent fraction of sulphate (EFSO4), at depths >2 m, were accompanied by rapid increases in equivalent fraction of chloride (EFCl), followed by nitrate (EFNO3). The stepwise regression for EFCl and EFNO3 indicated that nitrate retention was reduced by the pre-existing sulphate and imported chloride, whereas only sulphate reduced chloride adsorption. The results indicate that chloride and nitrate adsorption and retention occurred, in the order chloride>nitrate, in soils containing large amounts of sulphate under approximately similar total inputs of N- and Cl-fertilisers. (C) 2004 Elsevier B.V. All rights reserved.

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Sulfate (SO42-) is an important anion regulating many metabolic and cellular processes. Maintenance Of SO42- homeostasis occurs in the renal proximal tubule via membrane transport proteins. Two SO42- transporters that have been characterized and implicated in regulating serum SO42- levels are: NaSi- 1, a Na+-SO4 (2-) cotransporter located at the brush border membrane and Sat-1, a SO4 (2-) -anion exchanger located on the basolateral membranes of proximal tubular cells. Unlike Sat-1, for which very few studies have looked at regulation of its expression, NaSi- 1 has been shown to be regulated by various hormones and dietary conditions in vivo. To study this further, NaSj- I (SLC13A1) and Sat- I (SLC26A1) gene structures were determined and recent studies have characterized their respective gene promoters. This review presents the current understanding of the transcriptional regulation of NaSj- I and Sat- 1, and describes possible pathogenetic implications which arise as a consequence of altered SO(4)(2-)homeostasis. (c) 2005 Elsevier Ltd. All rights reserved.

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Sulfate plays an essential role in human growth and development. Here, we characterized the functional properties of the human Na+-sulfate cotransporter (hNaS2), determined its tissue distribution, and identified its gene (SLC13A4) structure. Expression of hNaS2 protein in Xenopus oocytes led to a Na+-dependent transport of sulfate that was inhibited by thiosulfate, phosphate, molybdate. selenate and tungstate, but not by oxalate, citrate, succinate, phenol red or DIDS. Transport kinetics of hNaS2 determined a K, for sulfate of 0.38 mM, suggestive of a high affinity sulfate transporter. Na+ kinetics determined a Hill coefficient of 1.6 +/- 0.6, suggesting a Na: SO42- stoichiometry of 2:1. hNaS2 mRNA was highly expressed in placenta and testis, with intermediate levels in brain and lower levels found in the heart, thymus, and liver. The SLC13A4 gene contains 16 exons, spanning over 47 kb in length. Its 5'-flanking region contains CAAT- and GC-box motifs, and a number of putative transcription factor binding sites, including GATA-1, AP-1, and AP-2 consensus sequences. This is the first study to characterize hNaS2 transport kinetics, define its tissue distribution, and resolve its gene (SLC13A4) structure and 5' flanking region. (C) 2004 Elsevier Inc. All rights reserved.

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The temperature dependence of the structure of the mixed-anion Tutton salt K-2[Cu(H2O)(6)](SO4)(2x)(SeO4)(2-2x) has been determined for crystals with 0, 17, 25, 68, 78, and 100% sulfate over the temperature range of 85-320 K. In every case, the [Cu(H2O)(6)](2+) ion adopts a tetragonally elongated coordination geometry with an orthorhombic distortion. However, for the compounds with 0, 17, and 25% sulfate, the long and intermediate bonds occur on a different pair of water molecules from those with 68, 78, and 100% sulfate. A thermal equilibrium between the two forms is observed for each crystal, with this developing more readily as the proportions of the two counterions become more similar. Attempts to prepare a crystal with approximately equal amounts of sulfate and selenate were unsuccessful. The temperature dependence of the bond lengths has been analyzed using a model in which the Jahn-Teller potential surface of the [Cu(H2O)(6)](2+) ion is perturbed by a lattice-strain interaction. The magnitude and sign of the orthorhombic component of this strain interaction depends on the proportion of sulfate to selenate. Significant deviations from Boltzmann statistics are observed for those crystals exhibiting a large temperature dependence of the average bond lengths, and this may be explained by cooperative interactions between neighboring complexes.

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Sulfate is an essential ion required for numerous functions in mammalian physiology. Due to its hydrophilic nature, cells require sulfate transporters on their plasma membranes to allow entry of sulfate into cells. In this study, we identified a new mouse Na+-sulfate cotransporter (mNaS2), characterized its tissue distribution and determined its cDNA and gene (Slc13a4) structures. mNaS2 mRNA was expressed in placenta, brain, lung, eye, heart, testis, thymus and liver. The mouse NaS2 cDNA spans 3384 nucleotides and its open frame encodes a protein of 624 amino acids. Slc13a4 maps to mouse chromosome 6131 and contains 16 exons, spanning over 40 kb in length. Its 5'-flanking region contains CART- and GC-box motifs and a number of putative transcription factor binding sites, including GATA-1, MTF-1, STAT6 and HNF4 consensus sequences. This is the first study to define the tissue distribution of mNaS2 and resolve its cDNA and gene structures, which will allow us to investigate mNaS2 gene expression in vivo and determine its role in mammalian physiology.