排序方式: 共有29条查询结果,搜索用时 15 毫秒
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Ectopic beta-chain of ATP synthase is an apolipoprotein A-I receptor in hepatic HDL endocytosis 总被引:12,自引:0,他引:12
Martinez LO Jacquet S Esteve JP Rolland C Cabezón E Champagne E Pineau T Georgeaud V Walker JE Tercé F Collet X Perret B Barbaras R 《Nature》2003,421(6918):75-79
The effect of high-density lipoprotein (HDL) in protecting against atherosclerosis is usually attributed to its role in 'reverse cholesterol transport'. In this process, HDL particles mediate the efflux and the transport of cholesterol from peripheral cells to the liver for further metabolism and bile excretion. Thus, cell-surface receptors for HDL on hepatocytes are chief partners in the regulation of cholesterol homeostasis. A high-affinity HDL receptor for apolipoprotein A-I (apoA-I) was previously identified on the surface of hepatocytes. Here we show that this receptor is identical to the beta-chain of ATP synthase, a principal protein complex of the mitochondrial inner membrane. Different experimental approaches confirm this ectopic localization of components of the ATP synthase complex and the presence of ATP hydrolase activity at the hepatocyte cell surface. Receptor stimulation by apoA-I triggers the endocytosis of holo-HDL particles (protein plus lipid) by a mechanism that depends strictly on the generation of ADP. We confirm this effect on endocytosis in perfused rat liver ex vivo by using a specific inhibitor of ATP synthase. Thus, membrane-bound ATP synthase has a previously unsuspected role in modulating the concentrations of extracellular ADP and is regulated by a principal plasma apolipoprotein. 相似文献
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Aharonian F Akhperjanian AG Bazer-Bachi AR Beilicke M Benbow W Berge D Bernlöhr K Boisson C Bolz O Borrel V Braun I Breitling F Brown AM Chadwick PM Chounet LM Cornils R Costamante L Degrange B Dickinson HJ Djannati-Ataï A Drury LO Dubus G Emmanoulopoulos D Espigat P Feinstein F Fontaine G Fuchs Y Funk S Gallant YA Giebels B Gillessen S Glicenstein JF Goret P Hadjichristidis C Hauser D Hauser M Heinzelmann G Henri G Hermann G Hinton JA Hofmann W Holleran M Horns D Jacholkowska A de Jager OC 《Nature》2006,439(7077):695-698
The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago. 相似文献
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Fiber Migration and Distribution of Twist at Different Radial Positions of Rotor Yarn-by Hi-Scope Video Microscope System 总被引:2,自引:0,他引:2
BackgroundIntheearly 195 0s,MortonandYen[1] developedthefibertracingmethodintheyarn .Theymixedsomedyedfibersintoyarnbeforecarding ,anddippedtheyarninachemicalreagentwithsimilarrefractiveindextoobservethedyedfibersintheyarnunderthemicroscope .Theconceptoffibe… 相似文献
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A high-resolution map of active promoters in the human genome 总被引:1,自引:0,他引:1
Kim TH Barrera LO Zheng M Qu C Singer MA Richmond TA Wu Y Green RD Ren B 《Nature》2005,436(7052):876-880
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Jacquet S Malaval C Martinez LO Sak K Rolland C Perez C Nauze M Champagne E Tercé F Gachet C Perret B Collet X Boeynaems JM Barbaras R 《Cellular and molecular life sciences : CMLS》2005,62(21):2508-2515
Cell surface receptors for high-density lipoprotein (HDL) on hepatocytes are major partners in the regulation of cholesterol
homeostasis. We recently identified a cell surface ATP synthase as a high-affinity receptor for HDL apolipoprotein A-I (apoA-I)
on human hepatocytes. Stimulation of this ectopic ATP synthase by apoA-I triggered a low-affinity-receptor-dependent HDL endocytosis
by a mechanism strictly related to the generation of ADP. This suggests that nucleotide G-protein- coupled receptors of the
P2Y family are molecular components in this pathway. Only P2Y1 and P2Y13 are present on the membrane of hepatocytes. Using both a pharmacological approach and small interference RNA, we identified
P2Y13 as the main partner in hepatic HDL endocytosis, in cultured cells as well as in situ in perfused mouse livers. We also found
a new important action of the antithrombotic agent AR-C69931MX as a strong activator of P2Y13-mediated HDL endocytosis.
Received 9 May 2005; received after revision 24 June 2005; accepted 1 September 2005 相似文献
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Valtonen MJ Lehto HJ Nilsson K Heidt J Takalo LO Sillanpää A Villforth C Kidger M Poyner G Pursimo T Zola S Wu JH Zhou X Sadakane K Drozdz M Koziel D Marchev D Ogloza W Porowski C Siwak M Stachowski G Winiarski M Hentunen VP Nissinen M Liakos A Dogru S 《Nature》2008,452(7189):851-853
Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later. 相似文献
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Jaydeep SARKAR Tien-Heng HUANG Lih-Ping WANG Peter H.McDONALD Chi-Fung LO Paul S.GILMAN 《中国科学:技术科学》2010,(4)
In this study we have used a combinatorial approach for producing binary and ternary alloy thin film libraries using a lab-scale RF co-sputtering system.Initially we used two elemental sputtering targets,i.e.aluminum(Al) target and neodymium(Nd) target,to produce a film library of varying composition and successfully identified a suitable composition range(1.95-2.38 at%Nd) in which resistance to hillock formation and resistivity of the film spots were found to be satisfactory in annealed state(350°C,30 min) .In another case,in order to form ternary alloy composition library we have used two sputtering targets,i.e.an Al-0.5 at%Nd alloy target and an elemental Ni target.Though,co-sputtered Al-0.6 at% Nd-0.9 at%Ni alloy films showed satisfactory resistance to hillock formation and low resistivity after annealing,film deposited from a ternary alloy target with the same composition failed to show satisfactory resistance to hillock formation during annealing.In case of Al-0.6 at%Nd-0.9 at%Ni alloy target,250 nm thick film showed poor resistance to hillock formation than the 500 nm thick film.This clearly showed thickness-dependent hillock performance of Al-0.6 at%Nd-0.9 at%Ni alloy.In this study it was found that,in addition to the process variables,metallurgical microstructure of the alloy sputtering targets had significant effect on the film properties which was not obvious from the results of films deposited using co-sputtering of the individual elemental targets. 相似文献