排序方式: 共有149条查询结果,搜索用时 15 毫秒
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Carlos A. Villalba-Galea Ludivine Frezza Walter Sandtner Francisco Bezanilla 《The Journal of general physiology》2013,142(5):543-555
Voltage control over enzymatic activity in voltage-sensitive phosphatases (VSPs) is conferred by a voltage-sensing domain (VSD) located in the N terminus. These VSDs are constituted by four putative transmembrane segments (S1 to S4) resembling those found in voltage-gated ion channels. The putative fourth segment (S4) of the VSD contains positive residues that likely function as voltage-sensing elements. To study in detail how these residues sense the plasma membrane potential, we have focused on five arginines in the S4 segment of the Ciona intestinalis VSP (Ci-VSP). After implementing a histidine scan, here we show that four arginine-to-histidine mutants, namely R223H to R232H, mediate voltage-dependent proton translocation across the membrane, indicating that these residues transit through the hydrophobic core of Ci-VSP as a function of the membrane potential. These observations indicate that the charges carried by these residues are sensing charges. Furthermore, our results also show that the electrical field in VSPs is focused in a narrow hydrophobic region that separates the extracellular and intracellular space and constitutes the energy barrier for charge crossing. 相似文献
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Dealing with paralogy in RADseq data: in silico detection and single nucleotide polymorphism validation in Robinia pseudoacacia L. 下载免费PDF全文
Cindy F. Verdu Erwan Guichoux Samuel Quevauvillers Olivier De Thier Yec'han Laizet Adline Delcamp Frédéric Gévaudant Arnaud Monty Annabel J. Porté Philippe Lejeune Ludivine Lassois Stéphanie Mariette 《Ecology and evolution》2016,6(20):7323-7333
The RADseq technology allows researchers to efficiently develop thousands of polymorphic loci across multiple individuals with little or no prior information on the genome. However, many questions remain about the biases inherent to this technology. Notably, sequence misalignments arising from paralogy may affect the development of single nucleotide polymorphism (SNP) markers and the estimation of genetic diversity. We evaluated the impact of putative paralog loci on genetic diversity estimation during the development of SNPs from a RADseq dataset for the nonmodel tree species Robinia pseudoacacia L. We sequenced nine genotypes and analyzed the frequency of putative paralogous RAD loci as a function of both the depth of coverage and the mismatch threshold allowed between loci. Putative paralogy was detected in a very variable number of loci, from 1% to more than 20%, with the depth of coverage having a major influence on the result. Putative paralogy artificially increased the observed degree of polymorphism and resulting estimates of diversity. The choice of the depth of coverage also affected diversity estimation and SNP validation: A low threshold decreased the chances of detecting minor alleles while a high threshold increased allelic dropout. SNP validation was better for the low threshold (4×) than for the high threshold (18×) we tested. Using the strategy developed here, we were able to validate more than 80% of the SNPs tested by means of individual genotyping, resulting in a readily usable set of 330 SNPs, suitable for use in population genetics applications. 相似文献
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C-6 opening of 5,6-cyclic sulfate derivatives of mannofuranose with a thiolate anion followed by acidic hydrolysis of the acyclic sulfate gave 6-S-alkyl derivatives in good yields (70-95%) and short reaction times (10-15min). This methodology was applied to the synthesis of methyl 2,3-O-isopropylidene-6-S-(2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl)-6-thio-alpha-d-mannofuranoside (70%), 2,3-O-isopropylidene-6-S-(2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl)-6-thio-alpha-d-mannofuranose (87%) and 2,3-O-isopropylidene-6-S-(1,2:3,4-di-O-isopropylidene-alpha-d-galactopyranos-6-yl)-6-thio-alpha-d-mannofuranose (87%). 相似文献
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Nogueira V Walter L Avéret N Fontaine E Rigoulet M Leverve XM 《Journal of bioenergetics and biomembranes》2002,34(1):55-66
Thyroid status is crucial in energy homeostasis, but despite extensive studies the actual mechanism by which it regulates mitochondrial respiration and ATP synthesis is still unclear. We studied oxidative phosphorylation in both intact liver cells and isolated mitochondria from in vivo models of severe not life threatening hyper- and hypothyroidism. Thyroid status correlated with cellular and mitochondrial oxygen consumption rates as well as with maximal mitochondrial ATP production. Addition of a protonophoric uncoupler, 2,4-dinitrophenol, to hepatocytes did not mimic the cellular energetic change linked to hyperthyroidism. Mitochondrial content of cytochrome oxidase, ATP synthase, phosphate and adenine nucleotide carriers were increased in hyperthyroidism and decreased in hypothyroidism as compared to controls. As a result of these complex changes, the maximal rate of ATP synthesis increased in hyperthyroidism despite a decrease in ATP/O ratio, while in hypothyroidism ATP/O ratio increased but did not compensate for the flux limitation of oxidative phosphorylation. We conclude that energy homeostasis depends on a compromise between rate and efficiency, which is mainly regulated by thyroid hormones. 相似文献
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Ribeiro N Tabaka H Peluso J Fetzer L Nebigil C Dumont S Muller CD Désaubry L 《Bioorganic & medicinal chemistry letters》2007,17(20):5523-5524
We synthesized 3-O-methylviridicatin and several analogues of this fungal metabolite. We showed that replacement of the methoxy moiety by a thiomethyl enhanced dramatically its ability to inhibit TNF-alpha secretion. These results strongly suggest that 4-phenyl-3-methylthioquinolinone may provide the basis for the development of new anti-inflammatory agents. 相似文献
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Laurent A Wright M Laayoun A Meunier B Tissot L Pitie M 《Nucleosides, nucleotides & nucleic acids》2007,26(8-9):927-930
For the first time Clip-Phen (1) was conjugated to oligonucleotides to provide very efficient tools for the cleavage of nucleic acids at specific positions. The synthesis of the conjugates as well as the cleavage experiments are reported. 相似文献
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CCL1-CCR8 interactions: an axis mediating the recruitment of T cells and Langerhans-type dendritic cells to sites of atopic skin inflammation 总被引:5,自引:0,他引:5
Gombert M Dieu-Nosjean MC Winterberg F Bünemann E Kubitza RC Da Cunha L Haahtela A Lehtimäki S Müller A Rieker J Meller S Pivarcsi A Koreck A Fridman WH Zentgraf HW Pavenstädt H Amara A Caux C Kemeny L Alenius H Lauerma A Ruzicka T Zlotnik A Homey B 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(8):5082-5091
Atopic dermatitis represents a chronically relapsing skin disease with a steadily increasing prevalence of 10-20% in children. Skin-infiltrating T cells, dendritic cells (DC), and mast cells are thought to play a crucial role in its pathogenesis. We report that the expression of the CC chemokine CCL1 (I-309) is significantly and selectively up-regulated in atopic dermatitis in comparison to psoriasis, cutaneous lupus erythematosus, or normal skin. CCL1 serum levels of atopic dermatitis patients are significantly higher than levels in healthy individuals. DC, mast cells, and dermal endothelial cells are abundant sources of CCL1 during atopic skin inflammation and allergen challenge, and Staphylococcus aureus-derived products induce its production. In vitro, binding and cross-linking of IgE on mast cells resulted in a significant up-regulation of this inflammatory chemokine. Its specific receptor, CCR8, is expressed on a small subset of circulating T cells and is abundantly expressed on interstitial DC, Langerhans cells generated in vitro, and their monocytic precursors. Although DC maintain their CCR8+ status during maturation, brief activation of circulating T cells recruits CCR8 from intracytoplamic stores to the cell surface. Moreover, the inflammatory and atopy-associated chemokine CCL1 synergizes with the homeostatic chemokine CXCL12 (SDF-1alpha) resulting in the recruitment of T cell and Langerhans cell-like DC. Taken together, these findings suggest that the axis CCL1-CCR8 links adaptive and innate immune functions that play a role in the initiation and amplification of atopic skin inflammation. 相似文献