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II Complexes (ii + complex)

Distribution by Scientific Domains
Medical Sciences42%
Life Sciences28%
Chemistry28%

Selected Abstracts

Uncompromised generation of a specific H-2DM-dependent peptide-MHC class,II complex from exogenous antigen in Leishmania mexicana -infected dendritic cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2003
Clare
Abstract Leishmania infection inhibits the capacity of macrophages (M,) to present antigens to CD4+ T cells. Relocation of MHC class,II and H-2DM to the parasitophorous vacuole (PV) and their subsequent degradation by the parasite may contribute to this defect. Dendritic cells (DC) are critical for initiation of primary T cell responses. DC can process Leishmania antigen and elicit Leishmania -specific T cells, but it is unknown whether exposure to Leishmania impairs this capacity. In particular, it is not clear whether DC containing live parasites efficiently process and present antigens. We investigated the ability of mouse bone marrow-derived DC infected with L. mexicana to generate pigeon cytochrome,c (PCC) peptide-MHC class II complexes, using the mAb D4, which recognizes PCC89,104 H-2Ek, and the PCC-specific T cell hybridoma 2B4. We show that H-2DM-dependent complex generation is not compromised by infection and that complexes are fully recognized by specific T cells. We further show that in contrast to infected M,, in infected DC cytoplasmic H-2DM is not down-regulated and not relocated to the parasite-containing vacuole. This observation may explain the continued ability of infected DC to present PCC, and also indicates differences in the habitat of these intracellular parasites in DC compared to M,. [source]

Structural analysis of photosystem II in far-red-light-adapted thylakoid membranes

FEBS JOURNAL, Issue 1 2000
New crystal forms provide evidence for a dynamic reorganization of light-harvesting antennae subunits
We studied two-dimensional crystals of the major pigment,protein complex, photosystem II, in far-red-light-adapted thylakoid membranes of the viridis-zb63 mutant of barley. Significantly larger grana membranes were produced with an increased synthesis of the entire photosystem II complex. These red-light-adapted membranes also contained two-dimensional crystals with a high frequency. Three different crystal forms of photosystem II were observed, providing the following data which further our understanding of the architecture of the native complex. (a) The oligomeric form of photosystem II in the membrane was monomeric in all crystal forms, but with a clear non-crystallographic pseudo-twofold symmetry. This was more apparent on the lumenal face of the complex. (b) The variability of unit cell contacts in different crystal forms implied that the peripheral light-harvesting antenna complex and the core of the complex were loosely connected. These peripheral subunits were predicted to rearrange so that they can either encircle the core complex or associate in parallel channels separated by lines of core complexes. (c) Grana membranes were found to retain a double-layered inside-out character, with a stromal face-to-stromal face packing. However, the presence of a crystal in one membrane did not necessarily impose crystallinity on its pair. [source]

Defective T-cell function leading to reduced antibody production in a kleisin-, mutant mouse

IMMUNOLOGY, Issue 2 2008
Katharine M. Gosling
Summary The recently described nessy (Ncaph2nes/nes) mutant mouse strain has a defect in T-cell development caused by a mutation in the ubiquitous kleisin-, (also known as Ncaph2). Kleisin- , is a subunit of the condensin II complex involved in chromosome condensation during mitosis. The nessy phenotype is characterized by CD44hi CD8+ peripheral T cells, 10,20% of normal thymocyte numbers and 2·5-fold fewer ,, T cells in the spleen compared with wild-type mice. In this study we examined the effect of the nessy mutation in kleisin-, on the immune response by challenging mice with an attenuated strain of Salmonella. Results showed that nessy mice control bacterial load as effectively as wild-type mice but exhibit a reduced antibody titre. Further experiments revealed that while the T-dependent antibody response was diminished in nessy mice the T-independent response was normal, suggesting that the defect was the result of T-cell function and not B-cell function. In vitro activation assays showed that nessy T cells have a lower capacity to up-regulate the early activation marker CD69 than wild-type T cells. Upon transfer into RAG,/, mice, nessy and wild-type CD4 T cells showed equivalent homeostatic proliferation, while nessy CD8 T cells proliferated more than their wild-type counterparts. When cultured with anti-T-cell receptor , or concanavalin A, nessy T cells were found to die faster than wild-type T cells. These data indicate that kleisin-, is required for a normal immune response, and represent the first demonstration of a role for kleisin-, in T-cell function. [source]

Separation of nuclear protein complexes by blue native polyacrylamide gel electrophoresis

ELECTROPHORESIS, Issue 7 2006
Zora Nováková
Abstract The nucleus is a highly structured organelle with distinct compartmentalization of specific functions. To understand the functions of these nuclear compartments, detailed description of protein complexes which form these structures is of crucial importance. We explored therefore the potential of blue native PAGE (BN-PAGE) method for the separation of nuclear protein complexes. We focused on (i),solubility and stability of nuclear complexes under conditions prerequisite for the separation by BN-PAGE, (ii),improved separation of native nuclear protein complexes using 2-D colorless native/blue native PAGE (CN-/BN-PAGE), and (iii),mass spectrometric analysis of protein complexes which were isolated directly from native 1-D or from 2-D CN/BN-PAGE gels. The suitability of BN-PAGE for nuclear proteomic research is demonstrated by the successful separation of polymerase,I and polymerase,II complexes, and by mass spectrometric determination of U1 small nuclear ribonucleoprotein particle composition. Moreover, practical advice for sample preparation is provided. [source]

Uncompromised generation of a specific H-2DM-dependent peptide-MHC class,II complex from exogenous antigen in Leishmania mexicana -infected dendritic cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2003
Clare
Abstract Leishmania infection inhibits the capacity of macrophages (M,) to present antigens to CD4+ T cells. Relocation of MHC class,II and H-2DM to the parasitophorous vacuole (PV) and their subsequent degradation by the parasite may contribute to this defect. Dendritic cells (DC) are critical for initiation of primary T cell responses. DC can process Leishmania antigen and elicit Leishmania -specific T cells, but it is unknown whether exposure to Leishmania impairs this capacity. In particular, it is not clear whether DC containing live parasites efficiently process and present antigens. We investigated the ability of mouse bone marrow-derived DC infected with L. mexicana to generate pigeon cytochrome,c (PCC) peptide-MHC class II complexes, using the mAb D4, which recognizes PCC89,104 H-2Ek, and the PCC-specific T cell hybridoma 2B4. We show that H-2DM-dependent complex generation is not compromised by infection and that complexes are fully recognized by specific T cells. We further show that in contrast to infected M,, in infected DC cytoplasmic H-2DM is not down-regulated and not relocated to the parasite-containing vacuole. This observation may explain the continued ability of infected DC to present PCC, and also indicates differences in the habitat of these intracellular parasites in DC compared to M,. [source]

Synthesis and crystal structure of 3,5-diacetyl-4-methylpyrazole

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2010
Moha Outirite
The 3,5-diacetyl-4-methylpyrazole diketone has been synthesized and its crystal structure has been determined. This diketone reacts with hydroxylamine hydrochloride to give the dioxime derivative. This reaction, conducted in presence of copper II ions, leads to the formation of L2M2 copper II complexes. J. Heterocyclic Chem., (2010). [source]

Peroxiredoxin Q of Arabidopsis thaliana is attached to the thylakoids and functions in context of photosynthesis,

THE PLANT JOURNAL, Issue 6 2006
Petra Lamkemeyer
Summary Peroxiredoxin Q (Prx Q) is one out of 10 peroxiredoxins encoded in the genome of Arabidopsis thaliana, and one out of four that are targeted to plastids. Peroxiredoxin Q functions as a monomeric protein and represents about 0.3% of chloroplast proteins. It attaches to the thylakoid membrane and is detected in preparations enriched in photosystem II complexes. Peroxiredoxin Q decomposes peroxides using thioredoxin as an electron donor with a substrate preference of H2O2 > cumene hydroperoxide , butyl hydroperoxide , linoleoyl hydroperoxide and insignificant affinity towards complex phospholipid hydroperoxide. Plants with decreased levels of Prx Q did not have an apparently different phenotype from wildtype at the plant level. However, similar to antisense 2-cysteine (2-Cys) Prx plants [Baier, M. et al. (2000)Plant Physiol., 124, 823,832], Prx Q-deficient plants had a decreased sensitivity to oxidants in a leaf slice test as indicated by chlorophyll a fluorescence measurements. Increased fluorescence ratios of photosystem II to I at 77 K and modified transcript levels of plastid- and nuclear-encoded proteins show that regulatory mechanisms are at work to compensate for the lack of Prx Q. Apparently Prx Q attaches to photosystem II and has a specific function distinct from 2-Cys peroxiredoxin in protecting photosynthesis. Its absence causes metabolic changes that are sensed and trigger appropriate compensatory responses. [source]