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101.
Juan F. Abenza Antonio Galindo Areti Pantazopoulou Concha Gil Vivian de los Ríos Miguel A. Pe?alva 《Molecular biology of the cell》2010,21(15):2756-2769
Aspergillus nidulans early endosomes display characteristic long-distance bidirectional motility. Simultaneous dual-channel acquisition showed that the two Rab5 paralogues RabB and RabA colocalize in these early endosomes and also in larger, immotile mature endosomes. However, RabB-GTP is the sole recruiter to endosomes of Vps34 PI3K (phosphatidylinositol-3-kinase) and the phosphatidylinositol-3-phosphate [PI(3)P] effector AnVps19 and rabBΔ, leading to thermosensitivity prevents multivesicular body sorting of endocytic cargo. Thus, RabB is the sole mediator of degradative endosomal identity. Importantly, rabBΔ, unlike rabAΔ, prevents early endosome movement. As affinity experiments and pulldowns showed that RabB-GTP recruits AnVps45, RabB coordinates PI(3)P-dependent endosome-to-vacuole traffic with incoming traffic from the Golgi and with long-distance endosomal motility. However, the finding that Anvps45Δ, unlike rabBΔ, severely impairs growth indicates that AnVps45 plays RabB-independent functions. Affinity chromatography showed that the CORVET complex is a RabB and, to a lesser extent, a RabA effector, in agreement with GST pulldown assays of AnVps8. rabBΔ leads to smaller vacuoles, suggesting that it impairs homotypic vacuolar fusion, which would agree with the sequential maturation of endosomal CORVET into HOPS proposed for Saccharomyces cerevisiae. rabBΔ and rabAΔ mutations are synthetically lethal, demonstrating that Rab5-mediated establishment of endosomal identity is essential for A. nidulans. 相似文献
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Andrea Vivian Alvarez-Oxiley Noelita Melo de Sousa Jean-Luc Hornick Kamal Touati Gysbert C van der Weijden Marcel AM Taverne Otto Szenci Jean-François Beckers 《Acta veterinaria Scandinavica》2010,52(1):9
Background
The involvement of placental lactogen (PL) in the regulation of foetal growth has been investigated in different species by in vivo immunomodulation techniques. However, when circulating antibodies are present together with the hormone, the procedure for hormonal measurement becomes considerably complex. The aim of this study was the immunoneutralization of bovine placental lactogen (bPL) concentrations in bovine foetal circulation by direct infusion of rabbit anti-bPL purified immunoglobulins (IgG) via a foetal catheter (in vivo study). The ability of a RIA based on guinea pig anti-bPL antiserum, for the measurement of bPL concentrations in samples containing exogenous rabbit anti-bPL immunoglobulins, was also analyzed in in vitro and in vivo conditions. 相似文献104.
105.
The biflavanone chamaejasmin has been isolated from the wood of Diphysa robinioides and its structure established by the spectral data of the biflavanone and its hexaacetyl derivative. 相似文献
106.
Thomas S Xue SA Cesco-Gaspere M San José E Hart DP Wong V Debets R Alarcon B Morris E Stauss HJ 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(9):5803-5810
We have previously described the functional activity of a human TCR specific for an HLA-A2-presented peptide derived from the Wilms tumor Ag 1 (WT1). Recent studies showed that the expression and function of human TCR was improved by the introduction of an additional disulfide bond between the alpha- and beta-chains or by the exchange of the human constant region for murine sequences. In this study, we analyzed the functional activity of WT1-TCR variants expressed in Jurkat cells and in primary T cells. The introduction of cysteine residues or murine constant sequences into the WT1-TCR did not result in a global reduction of mispairing with wild-type TCR chains. Instead, the level of mispairing was affected by the variable region sequences of the wild-type TCR chains. The analysis of freshly transduced peripheral blood T cells showed that the transfer of modified TCR constructs generated a higher frequency of Ag-responsive T cells than the transfer of the wild-type TCR. After several rounds of peptide stimulation this difference was no longer observed, as all transduced T cell populations accumulated approximately 90% of Ag-responsive T cells. Although the Ag-responsive T cells expressing the modified TCR bound the HLA-A2/WT1 tetramer more efficiently than T cells expressing the wild-type TCR, this did not improve the avidity of transduced T cells nor did it result in a measurable enhancement in IFN-gamma production and cytotoxic activity. This indicated that the enhanced tetramer binding of modified WT1-TCR variants was not associated with improved WT1-specific T cell function. 相似文献
107.
The inner cavity of Escherichia coli DegP protein is not essential for molecular chaperone and proteolytic activity 下载免费PDF全文
Jomaa A Damjanovic D Leong V Ghirlando R Iwanczyk J Ortega J 《Journal of bacteriology》2007,189(3):706-716
The Escherichia coli DegP protein is an essential periplasmic protein for bacterial survival at high temperatures. DegP has the unusual property of working as a chaperone below 28 degrees C, but efficiently degrading unfolded proteins above 28 degrees C. Monomeric DegP contains a protease domain and two PDZ domains. It oligomerizes into a hexameric cage through the staggered association of trimers. The active sites are located in a central cavity that is only accessible laterally, and the 12 PDZ domains act as mobile sidewalls that mediate opening and closing of the gates. As access to the active sites is restricted, DegP is an example of a self-compartmentalized protease. To determine the essential elements of DegP that maintain the integrity of the hexameric cage, we constructed several deletion mutants of DegP that formed trimers rather than hexamers. We found that residues 39 to 78 within the LA loops, as well as the PDZ2 domains are essential for the integrity of the DegP hexamer. In addition, we asked whether an enclosed cavity or cage of specific dimensions is required for the protease and chaperone activities in DegP. Both activities were maintained in the trimeric DegP mutants without an enclosed cavity and in deletion DegP mutants with significantly reduced dimensions of the cage. We conclude that the functional unit for the protease and chaperone activities of DegP is a trimer and that neither a cavity of specific dimensions nor the presence of an enclosed cavity appears to be essential for the protease and chaperone activities of DegP. 相似文献
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Differential recovery of peptides from sample tubes and the reproducibility of quantitative proteomic data 总被引:1,自引:0,他引:1
Differential recovery of peptides due to nonspecific adsorption can seriously compromise reproducibility and quality of proteomic data for peptide analyses by liquid chromatography-mass spectrometry (LC-MS). This study demonstrates large variations in reproducibility and quantitation of LC-MS data for peptides derived from tryptic digests of BSA upon storage in different sample tubes. Notably, we show that highly improved consistency and lower errors in quantitation of BSA tryptic peptides in replicate measurements is achieved with low-retention tubes compared to regular eppendorf tubes. Furthermore, qualitative differences in peptides detected by LC-MS were observed in the two types of storage tubes. These results illustrate the necessity for careful evaluation of storage vessels and conditions to minimize variability in sample quality for LC-MS experiments. 相似文献