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1.
Richards DM Dalheimer SL Ehst BD Vanasek TL Jenkins MK Hertz MI Mueller DL 《Journal of immunology (Baltimore, Md. : 1950)》2004,172(6):3469-3479
Ag recognition by OVA-reactive OT-II (I-Ab restricted) and DO11.10 (I-Ad restricted) TCR-Tg CD4+ T cells after heterotopic transplantation of OVA transgene-expressing tracheal grafts was examined as a model of minor histocompatibility Ag (mHAg)-induced chronic allograft rejection. In response to airway allotransplantation with grafts expressing the OVA transgene, these TCR-Tg CD4+ T cells expressed the activation markers CD69 and CD44, demonstrated evidence of blastogenesis, underwent multiple rounds of cell division leading to their clonal expansion in the draining lymph node, and proceeded to differentiate to a effector/memory T cell phenotype based on a reduction in the expression of CD45RB. These mHAg-specific TCR-Tg CD4+ T cells responded equally well to fully MHC-mismatched tracheas and to class II-deficient allografts, demonstrating that donor mHAg recognition by recipient CD4+ T cells does not rely on Ag presentation by donor-derived APC. The activation of mHAg-specific TCR-Tg CD4+ T cells after their adoptive transfer into recipient mice given MHC-matched, but mHAg-disparate, airway allografts was associated with their movement into the allograft and the near uniform destruction of the transplanted airway tissue secondary to the development of obliterative airways disease. These results demonstrate that an activation of mHAg-reactive CD4+ T cells in the draining lymph node by recipient APC that indirectly express graft mHAg-derived peptide/class II MHC complexes precedes responder T cell proliferation and differentiation, and leads to the eventual migration of these alloreactive T cells to the transplanted airway tissue and the promotion of chronic graft rejection. 相似文献
2.
Background
Protein translocation across the membrane of the Endoplasmic Reticulum (ER) is the first step in the biogenesis of secretory and membrane proteins. Proteins enter the ER by the Sec61 translocon, a proteinaceous channel composed of three subunits, α, β and γ. While it is known that Sec61α forms the actual channel, the function of the other two subunits remains to be characterized.Results
In the present study we have investigated the function of Sec61β in Drosophila melanogaster. We describe its role in the plasma membrane traffic of Gurken, the ligand for the Epidermal Growth Factor (EGF) receptor in the oocyte. Germline clones of the mutant allele of Sec61β show normal translocation of Gurken into the ER and transport to the Golgi complex, but further traffic to the plasma membrane is impeded. The defect in plasma membrane traffic due to absence of Sec61β is specific for Gurken and is not due to a general trafficking defect.Conclusion
Based on our study we conclude that Sec61β, which is part of the ER protein translocation channel affects a post-ER step during Gurken trafficking to the plasma membrane. We propose an additional role of Sec61β beyond protein translocation into the ER. 相似文献3.
Sequence of a cDNA for mouse thymidylate synthase reveals striking similarity with the prokaryotic enzyme 总被引:11,自引:0,他引:11
Perryman SM; Rossana C; Deng TL; Vanin EF; Johnson LF 《Molecular biology and evolution》1986,3(4):313-321
We report the nucleotide sequence of a cloned cDNA, pMTS-3, that contains a
1-kb insert corresponding to mouse thymidylate synthase (E.C. 2.1.1.45).
The open reading frame of 921 nucleotides from the first AUG to the
termination codon specifies a protein with a molecular mass of 34,962
daltons. The predicted amino acid sequence is 90% identical with that of
the human enzyme. The mouse sequence also has an extremely high degree of
similarity (as much as 55% identity) with prokaryotic thymidylate synthase
sequences, indicating that thymidylate synthase is among the most highly
conserved proteins studied to date. The similarity is especially pronounced
(as much as 80% identity) in the 44-amino-acid region encompassing the
binding site for deoxyuridylic acid. The cDNA sequence also suggests that
mouse thymidylate synthase mRNA lacks a 3' untranslated region, since the
termination codon, UAA, is followed immediately by a poly(A) segment.
相似文献
4.
5.
T L Vanasek A Khoruts T Zell D L Mueller 《Journal of immunology (Baltimore, Md. : 1950)》2001,167(10):5636-5644
CD4(+) T cells that undergo multiple rounds of cell division during primary Ag challenge in vivo produce IL-2 on secondary Ag rechallenge, whereas cells that fail to progress through the cell cycle are anergic to restimulation. Anti-CTLA-4 mAb treatment during primary Ag exposure increases cell cycle progression and enhances recall Ag responsiveness; however, simultaneous treatment with rapamycin, an inhibitor of the mammalian target of rapamycin and potent antiproliferative agent, prevents both effects. The data suggest that cell cycle progression plays a primary role in the regulation of recall Ag responsiveness in CD4(+) T cells in vivo. CTLA-4 molecules promote clonal anergy development only indirectly by limiting cell cycle progression during the primary response. 相似文献
6.
Role of the reticulum in the stability and shape of the isolated human erythrocyte membrane 总被引:12,自引:7,他引:5 下载免费PDF全文
In order to examine the widely held hypothesis that the reticulum of proteins which covers the cytoplamsic surface of the human erythrocyte membrane controls cell stability and shape, we have assessed some of its properties. The reticulum, freed of the bilayer by extraction with Triton X-100, was found to be mechanically stable at physiological ionic strength but physically unstable at low ionic strength. The reticulum broke down after a characteristic lag period which decreased 500-fold between 0 degrees and 37 degrees C. The release of polypeptide band 4.1 from the reticulum preceded that of spectrin and actin, suggesting that band 4.1 might stabilize the ensemble but is not essential to its integrity. The time-course of breakdown was similar for ghosts, the reticulum inside of ghosts, and the isolated reticulum. However, at very low ionic strength, the reticulum was less stable within the ghost than when free; at higher ionic strength, the reverse was true. Over a wide range of conditions the membrane broke down to vesicles just as the reticulum disintegrated, presumably because the bilayer was mechanically stabilized by this network. The volume of both ghosts and naked reticula varied inversely and reversibly with ionic strength. The volume of the naked reticulum varied far more widely than the ghost, suggesting that its deformation was normally limited by the less extensible bilayer. The contour of the isolated reticulum was discoid and often dimpled or indented, as visualized in the fluorescence microscope after labeling of the ghosts with fluoroscein isothiocyanate. Reticula derived from ghosts which had lost the ability to crenate in isotonic saline were shriveled, even though the bilayer was smooth and expanded. Conversly, ghosts crenated by dinitrophenol yielded smooth, expanded reticula. We conclude that the reticulum is a durable, flexible, and elastic network which assumes and stabilizes the contour of the membrane but is not responsible for its crenation. 相似文献
7.
Molecular evolution of a multigene family in group A streptococci 总被引:15,自引:0,他引:15
The emm genes are members of a gene family in group A streptococci (GAS)
that encode for antiphagocytic cell-surface proteins and/or
immunoglobulin-binding proteins. Previously sequenced genes in this family
have been named "emm," "fcrA," "enn," "arp," "protH," and "mrp"; herein
they will be referred to as the "emm gene family." The genes in the emm
family are located in a cluster occupying 3-6 kb between the genes mry and
scpA on the chromosome of Streptococcus pyogenes. Most GAS strains contain
one to three tandemly arranged copies of emm-family genes in the cluster,
but the alleles within the cluster vary among different strains.
Phylogenetic analysis of the conserved sequences at the 3' end of these
genes differentiates all known members of this family into four
evolutionarily distinct emm subfamilies. As a starting point to analyze how
the different subfamilies are related evolutionarily, the structure of the
emm chromosomal region was mapped in a number of diverse GAS strains by
using subfamily-specific primers in the polymerase chain reaction. Nine
distinct chromosomal patterns of the genes in the emm gene cluster were
found. These nine chromosomal patterns support a model for the evolution of
the emm gene family in which gene duplication followed by sequence
divergence resulted in the generation of four major-gene subfamilies in
this locus.
相似文献
8.
Brigida TL Lucena Billy M dos Santos João LS Moreira Ana Paula B Moreira Alvaro C Nunes Vasco Azevedo Anderson Miyoshi Fabiano L Thompson Marcos Antonio de MoraisJunior 《BMC microbiology》2010,10(1):298
Background
Bacteria may compete with yeast for nutrients during bioethanol production process, potentially causing economic losses. This is the first study aiming at the quantification and identification of Lactic Acid Bacteria (LAB) present in the bioethanol industrial processes in different distilleries of Brazil. 相似文献9.
CD25+Foxp3+ regulatory T cells facilitate CD4+ T cell clonal anergy induction during the recovery from lymphopenia 总被引:5,自引:0,他引:5
Vanasek TL Nandiwada SL Jenkins MK Mueller DL 《Journal of immunology (Baltimore, Md. : 1950)》2006,176(10):5880-5889
T cell clonal anergy induction in lymphopenic nu/nu mice was found to be ineffective. Exposure to a tolerizing peptide Ag regimen instead induced aggressive CD4(+) cell cycle progression and increased Ag responsiveness (priming). Reconstitution of T cell-deficient mice by an adoptive transfer of mature peripheral lymphocytes was accompanied by the development of a CD25(+)Foxp3(+)CTLA-4(+)CD4(+) regulatory T cell population that acted to dampen Ag-driven cell cycle progression and facilitate the induction of clonal anergy in nearby responder CD25(-)CD4(+) T cells. Thus, an early recovery of CD25(+) regulatory T cells following a lymphopenic event can prevent exuberant Ag-stimulated CD4(+) cell cycle progression and promote the development of clonal anergy. 相似文献
10.
Geoffrey TL Kloppenburg Rick de Graaf Gert ELM Grauls Cathrien A Bruggeman Frank R Stassen 《BMC microbiology》2007,7(1):111