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排序方式: 共有220条查询结果,搜索用时 15 毫秒
1.
Immunological identification of yeast SCO1 protein as a component of the inner mitochondrial membrane 总被引:4,自引:0,他引:4
Summary The SCO1 gene of Saccharomyces cerevisiae encodes a 30 kDa protein which is specifically required for a post-translational step in the accumulation of subunits 1 and 2 of cytochrome c oxidase (COXI and COXII). Antibodies directed against a -Gal::SCO1 fusion protein detect SCO1 in the mitochondrial fraction of yeast cells. The SCO1 protein is an integral membrane protein as shown by its resistance to alkaline extraction and by its solubilization properties upon treatment with detergents. Based on the results obtained by isopycnic sucrose gradient centrifugation and by digitonin treatment of mitochondria, SCO1 is a component of the inner mitochondrial membrane. Membrane localization is mediated by a stretch of 17 hydrophobic amino acids in the amino-terminal region of the protein. A truncated SCO1 derivative lacking this segment, is no longer bound to the membrane and simultaneously loses its biological function. The observation that membrane localization of SCO1 is affected in mitochondria of a rho
0 strain, hints at the possible involvement of mitochondrially coded components in ensuring proper membrane insertion. 相似文献
2.
Francis V. DeFeudis Lucienne Ossola Gaby Schmitt Paul Mandel 《Journal of neurochemistry》1980,34(4):845-849
Abstract: The effects of some GABA analogues and some drugs on the binding of [3H]muscimol (3.08 nM) to thoroughly washed subcellular particles prepared from a neuron-enriched culture of embryonic rat brain were examined using Na+-free Tris-citrate medium and a centrifugation method. Competition for [3H]muscimol binding sites by excess(10?5 M) unlabelled GABA provided estimates of “specific” binding. In accord with in vivo neuropharmacological studies on GABA receptors and with in vitro studies on cerebral membrane preparations, [3H]muscimol binding was potently inhibited by muscimol itself (IC50, 2.5 nM), GABA (1C50, 43 nM), isoguvacine (IC50, 61 nM), and 3-aminopropanesulphonic acid (IC50, 160 nM), and less potently inhibited by the GABA antagonist bicuculline methobromide (IC50, 800 nM). δ- Aminovaleric acid (IC50, 2.6 μM), the glycinelp-alanine antagonist strychnine (IC50, 6.6 μM), and the predominantly glial GABA uptake inhibitors β-alanine (IC50, 23 μM) and p-proline (IC50, 66 μM) also inhibited [3H]muscimol binding. Other inhibitors of Na+-dependent GABA uptake, (±)-nipecotic acid, L- 2,4-diaminobutyric acid, and guvacine, as well as picrotoxinin, were relatively inactive as inhibitors of [3H]muscimol binding (IC50≥ 1 mM). In addition to revealing that GABA receptors are present on neuronal membranes before the formation of most synapses, this binding of [3H]muscimol that occurs to neuronal, but not to glial, membranes might be useful as a “neuronal marker” and for the further characterization and isolation of GABA receptors. 相似文献
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5.
Silvia Lorente-Cebrián Niklas Mejhert Agné Kulyté Jurga Laurencikiene Gaby ?str?m Pér Hedén Mikael Rydén Peter Arner 《PloS one》2014,9(1)
MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and have multiple effects in various tissues including adipose inflammation, a condition characterized by increased local release of the pro-lipolytic cytokine tumor necrosis factor-alpha (TNF-α). Whether miRNAs regulate adipocyte lipolysis is unknown. We set out to determine whether miRNAs affect adipocyte lipolysis in human fat cells. To this end, eleven miRNAs known to be present in human adipose tissue were over-expressed in human in vitro differentiated adipocytes followed by assessments of TNF-α and glycerol levels in conditioned media after 48 h. Three miRNAs (miR-145, -26a and let-7d) modulated both parameters in parallel. However, while miR-26a and let-7d decreased, miR-145 increased both glycerol release and TNF-α secretion. Further studies were focused therefore on miR-145 since this was the only stimulator of lipolysis and TNF-α secretion. Time-course analysis demonstrated that miR-145 over-expression up-regulated TNF-α expression/secretion followed by increased glycerol release. Increase in TNF-α production by miR-145 was mediated via activation of p65, a member of the NF-κB complex. In addition, miR-145 down-regulated the expression of the protease ADAM17, resulting in an increased fraction of membrane bound TNF-α, which is the more biologically active form of TNF-α. MiR-145 overexpression also increased the phosphorylation of activating serine residues in hormone sensitive lipase and decreased the mRNA expression of phosphodiesterase 3B, effects which are also observed upon TNF-α treatment in human adipocytes. We conclude that miR-145 regulates adipocyte lipolysis via multiple mechanisms involving increased production and processing of TNF-α in fat cells. 相似文献
6.
N Otting N de Groot AJ de Vos-Rouweler A Louwerse GG Doxiadis RE Bontrop 《Immunogenetics》2012,64(10):755-765
Cynomolgus macaques (Macaca fascicularis) are used widely in biomedical research, and the genetics of their MHC (Mhc-Mafa) has become the focus of considerable attention in recent years. The cohort of Indonesian pedigreed macaques that we present here was typed for Mafa-A, -B, and -DR, by sequencing, as described in earlier studies. Additionally, the DRB region of these animals was characterised by microsatellite analyses. In this study, full-length sequencing of Mafa-DPA/B and -DQA/B in these animals was performed. A total of 75 different alleles were observed; 22 of which have not previously been reported, plus 18 extended exon 2 alleles that were already known. Furthermore, two microsatellites, D6S2854 and D6S2859, were used to characterise the complex Mafa-A region. Sequencing and segregation analyses revealed that the length patterns of these microsatellites are unique for each Mafa-A haplotype. In this work, we present a pedigreed colony of approximately 120 cynomolgus macaques; all of which are typed for the most significant polymorphic MHC class I and class II markers. Offspring of these pedigreed animals are easily characterised for their MHC by microsatellite analyses on the Mafa-A and -DRB regions, which makes the cumbersome sequencing analyses redundant. 相似文献
7.
The multidrug exporter AcrB is the inner membrane component of the AcrAB-TolC drug efflux system in Escherichia coli and is responsible for the resistance of this organism to a wide range of drugs. Here we describe the crystal structure of the trimeric AcrB in complex with a designed ankyrin-repeat protein (DARPin) inhibitor at 2.5-Å resolution. The three subunits of AcrB are locked in different conformations revealing distinct channels in each subunit. There seems to be remote conformational coupling between the channel access, exit, and the putative proton-translocation site, explaining how the proton motive force is used for drug export. Thus our structure suggests a transport pathway not through the central pore but through the identified channels in the individual subunits, which greatly advances our understanding of the multidrug export mechanism. 相似文献
8.
Palmer G Burger D Mezin F Magne D Gabay C Dayer JM Guerne PA 《Arthritis research & therapy》2004,6(3):R181-R189
Leflunomide is an immunomodulatory agent used for the treatment of rheumatoid arthritis. In this study, we investigated the
effect of A77 1726 – the active metabolite of leflunomide – on the production of IL-1 receptor antagonist (IL-1Ra) by human
synovial fibroblasts and articular chondrocytes. Cells were incubated with A77 1726 alone or in combination with proinflammatory
cytokines. IL-1Ra production was determined by ELISA. A77 1726 alone had no effect, but in the presence of IL-1β or tumour
necrosis factor-α it markedly enhanced the secretion of IL-1Ra in synovial fibroblasts and chondrocytes. The effect of A77
1726 was greatest at 100 μmol/l. In synovial fibroblasts and de-differentiated chondrocytes, A77 1726 also increased IL-1β-induced
IL-1Ra production in cell lysates. Freshly isolated chondrocytes contained no significant amounts of intracellular IL-1Ra.
A77 1726 is a known inhibitor of pyrimidine synthesis and cyclo-oxygenase (COX)-2 activity. Addition of exogenous uridine
did not significantly modify the effect of A77 1726 on IL-1Ra production, suggesting that it was not mediated by inhibition
of pyrimidine synthesis. Indomethacin increased IL-1β-induced IL-1Ra secretion in synovial fibroblasts and de-differentiated
chondrocytes, suggesting that inhibition of COX-2 may indeed enhance IL-1β-induced IL-1Ra production. However, the stimulatory
effect of indomethacin was consistently less effective than that of A77 1726. A77 1726 increases IL-1Ra production by synovial
fibroblasts and chondrocytes in the presence of proinflammatory cytokines, and thus it may possess chondroprotective effects.
The effect of A77 1726 may be partially mediated by inhibition of COX-2, but other mechanisms likely concur to stimulate IL-1Ra
production. 相似文献
9.
Arguedas Cortés D Dolz G Romero Zúñiga JJ Jiménez Rocha AE León Alán D 《Revista de biología tropical》2010,58(4):1453-1465
Centrocestusformosanus is a zoonotic trematode from Asia and has been mainly associated as cause of death of cultured fish. To identify pathogen trematode species in tilapia fry (Oreochromis niloticus) and to determine mollusks hosting these parasites, freshwater mollusks were collected from tilapia cultured ponds and experimental infections were carried out with tilapia fries and different mollusk species. A total of 907 freshwater mollusks were obtained from tilapia ponds and were identified to species level, four gastropods and one bivalve were determined: Melania tuberculata, Melanoides turricula, Pomacea flagellata, Haitia cubensis and Anodontiles luteola. For the first time, the presence of M. turricula and H. cubensis are reported in Costa Rica. Seven morphotypes of cercariae (Xifiodiocercaria, Equinostoma, Oftalmocercaria, Parapleurolofocercus, Cistocerca, Furcocercaria and Leptocercaria) parasitizing all five species of mollusks were found, all of distome type. Experimental exposure of tilapia fry to M. tuberculata demonstrated that the parapleurolofocercus morphotype found in the mollusk is in accordance with the finding of C. formosanus in tilapia fry. An abundance and mean intensity of 1018-1027 digeneans per gill in each exposed fish was determined. Centrocestus formosanus is reported for the first time in Costa Rica, for which the primary and secondary intermediate hosts were also determined. 相似文献
10.
Banning A Schnurr K Böl GF Kupper D Müller-Schmehl K Viita H Ylä-Herttuala S Brigelius-Flohé R 《Free radical biology & medicine》2004,36(2):135-144
Cytokines or hydroperoxides upregulate cell adhesion molecules (CAM) in early stages of atherosclerosis. VCAM-1 expression was therefore investigated in rabbit aortic smooth muscle cells (SMC) stably transfected either with phospholipid hydroperoxide glutathione peroxidase (PHGPx; SMCPHGPx) as a hydroperoxide-reducing enzyme or with 15-lipoxygenase (15-LOX; SMCLOX) as a hydroperoxide-producing enzyme. Transfected cells showed up to 3-fold enhanced PHGPx and a marked LOX activity, respectively, that was absent in controls. Intracellular hydroperoxides were 6-fold higher in SMCLOX than in SMC or SMCPHGPx. Intracellular protein thiols were decreased by 50 and 90% in SMCPHGPx and SMCLOX, respectively. Glutathione mixed disulfides were tentatively increased from SMC via SMCPHGPx to SMCLOX, accordingly. Thiol reduction with tris(2-carboxyethyl)phosphine completely restored protein thiols in SMCPHGPx, whereas in SMCLOX only 60% of control values were recovered. Basal VCAM-1 mRNA levels were decreased by 50% in SMCPHGPx and 75% in SMCLOX. VCAM-1-inducibility was abrogated in SMCLOX but not in SMCPHGPx. Accordingly, NFkappaB-driven reporter gene activation by IL-1 was unaffected in SMCPHGPx but abolished in SMCLOX. The data confirm that PHGPx overexpression dampens CAM expression either by lowering stimulatory hydroperoxides or by using hydroperoxides for protein modification. But hydroperoxides, when constitutively overproduced as in SMCLOX, inhibit CAM expression and render cells refractory to IL-1 stimulation likely due to oxidation of protein thiols of the signaling system. 相似文献