Search results for "glycoproteins"
showing 10 items of 496 documents
Macrophages Escape Inhibition of Major Histocompatibility Complex Class I-Dependent Antigen Presentation by Cytomegalovirus
2000
ABSTRACTThe mouse cytomegalovirus (MCMV)m152- andm06-encoded glycoproteins gp40 and gp48, respectively, independently downregulate major histocompatibility complex (MHC) class I surface expression during the course of productive MCMV infection in fibroblasts. As a result, presentation of an immediate-early protein pp89-derived nonapeptide toH-2Ld-restricted CD8+cytotoxic T cells is completely prevented in fibroblasts. Here we demonstrate that MCMV-infected primary bone marrow macrophages and the macrophage cell line J774 constitutively present pp89 peptides during permissive MCMV infection to cytotoxic T lymphocytes (CTL). In contrast to fibroblasts, expression of them152andm06genes in macr…
Human papillomavirus infection requires cell surface heparan sulfate.
2001
ABSTRACT Using pseudoinfection of cell lines, we demonstrate that cell surface heparan sulfate is required for infection by human papillomavirus type 16 (HPV-16) and HPV-33 pseudovirions. Pseudoinfection was inhibited by heparin but not dermatan or chondroitin sulfate, reduced by reducing the level of surface sulfation, and abolished by heparinase treatment. Carboxy-terminally deleted HPV-33 virus-like particles still bound efficiently to heparin. The kinetics of postattachment neutralization by antiserum or heparin indicated that pseudovirions were shifted on the cell surface from a heparin-sensitive into a heparin-resistant mode of binding, possibly involving a secondary receptor. Alpha-6…
Mast cells are crucial for early inflammation, migration of Langerhans cells, and CTL responses following topical application of TLR7 ligand in mice.
2007
Abstract Until recently, IgE-activated mast cells have been regarded merely as effector cells of adaptive immune responses, involved in allergic reactions and mucosal immunity to parasites. Herein, we report that murine dermal mast cells, activated by local administration of a cream containing the synthetic TLR7 ligand imiquimod, are essential to initiate an early inflammatory reaction. The mast-cell–derived cytokines TNF-α and IL-1β play an important role in this process. Furthermore, TLR7-activated mast cells are also able to promote the emigration of Langerhans cells, which partly depends on the expression of mast-cell–derived IL-1β. We have previously shown that TLR7 ligation enhances t…
Identification of a 58-kilodalton cell surface fibrinogen-binding mannoprotein from Candida albicans.
1992
Treatment of both yeast (blastoconidia) and hyphal (blastoconidia with germ tubes) cells of Candida albicans with beta-mercaptoethanol (beta ME) releases a complex array of cell wall-bound proteins and glycoproteins. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblotting with fibrinogen-anti-fibrinogen antibody allowed the identification of a 58-kDa mannoprotein (mp58) in both extracts which specifically interacts with human fibrinogen. Treatment of intact cells with low concentrations of beta-glucanase (Zymolyase 20T) for short periods or with beta ME abolished or significantly reduced binding of fibrinogen. A rabbit polyclonal antiserum was raised…
Relationship between within-host fitness and virulence in the vesicular stomatitis virus: correlation with partial decoupling.
2012
ABSTRACT Given the parasitic nature of viruses, it is sometimes assumed that rates of viral replication and dissemination within hosts (within-host fitness) correlate with virulence. However, there is currently little empirical evidence supporting this principle. To test this, we quantified the fitness and virulence of 21 single- or double-nucleotide mutants of the vesicular stomatitis virus in baby hamster kidney cells (BHK-21). We found that, overall, these two traits correlated positively, but significant outliers were identified. Particularly, a single mutation in the conserved C terminus of the N nucleocapsid (U1323A) had a strongly deleterious fitness effect but did not alter or even …
Biosynthesis of Lipopolysaccharide-Binding Protein in Rabbit Hepatocytes
1990
Studies reported here show that the recently discovered acute-phase protein, lipopolysaccharide-binding protein (LBP), is synthesized by hepatocytes. For these studies, explanted rabbit hepatocytes were grown in the presence of 35S-methionine. Biosynthetically labelled LBP in the cells and supernatant was identified using immunoprecipitation with rat anti-rabbit LBP antibody. This antibody immunoprecipitates both the LBP polypeptide and the glycosylated protein. With a cell-free translation system a comparison of RNA from normal rabbit liver with that isolated from acute-phase rabbit liver indicated that a translatable LBP message is only found in the RNA from acute-phase liver. Studies wit…
Protein Kinase C μ Is Regulated by the Multifunctional Chaperon Protein p32
2000
We identified the multifunctional chaperon protein p32 as a protein kinase C (PKC)-binding protein interacting with PKCalpha, PKCzeta, PKCdelta, and PKC mu. We have analyzed the interaction of PKC mu with p32 in detail, and we show here in vivo association of PKC mu, as revealed from yeast two-hybrid analysis, precipitation assays using glutathione S-transferase fusion proteins, and reciprocal coimmunoprecipitation. In SKW 6.4 cells, PKC mu is constitutively associated with p32 at mitochondrial membranes, evident from colocalization with cytochrome c. p32 interacts with PKC mu in a compartment-specific manner, as it can be coimmunoprecipitated mainly from the particulate and not from the so…
RT-PCR and in situ hybridization analysis of apolipoprotein H expression in rat normal tissues
2006
In this study, by using different techniques (i.e. Northern blot hybridization, RT-PCR and Southern blot hybridization) on various normal rat tissues, we were able to identify liver, kidney, heart, small intestine, brain, spleen, stomach and prostate as tissues in which the ApoH gene is transcribed. Moreover, for some of these tissues, by in situ hybridization, we found a specific localization of apoH transcripts. For instance epithelial cells of the bile ducts in liver and of the proximal tubules in kidney are the major sites of apoH synthesis. Our data suggest that some of the different physiological roles proposed for apoH could correlate with its direct expression, while others could co…
Quaternary and subunit structure of Calliphora arylphorin as deduced from electron microscopy, electrophoresis, and sequence similarities with arthro…
1992
Arylphorin was purified from larvae of the blowfly Calliphora vicina and studied in its oligomeric form and after dissociation at pH 9.6 into native subunits. In accordance with earlier literature, it was electrophoretically shown to be a 500 kDa hexamer (1 x 6) consisting of 78 kDa polypeptides (= subunits). Electron micrographs of negatively stained hexamers show a characteristic curvilinear, equilateral triangle of 12 nm in diameter (top view) and a rectangle measuring 10 x 12 nm (side view). Alternatively, particles in the top view orientation exhibit a roughly circular shape 12 nm in diameter. Crossed immunoelectrophoresis revealed the presence of a major subunit type; the nature of a …
On the origin of Metazoan adhesion receptors: cloning of integrin alpha subunit from the sponge Geodia cydonium
1997
Integrins are prominent receptors known from vertebrates and the higher phyla of invertebrates. Until now, no evidence has been provided for the existence of integrins in the lowest Metazoa, the sponges (Porifera). We have isolated and characterized a cDNA clone encoding the alpha subunit of integrin from the marine sponge Geodia cydonium (GCINTEG). The open reading frame encodes a polypeptide of 1,086 residues (118 kDa). The intracellular domain features the sequence Tyr-Phe-x-Gly-Phe-Phe-x-Arg, which is different in one residue from the characteristic consensus pattern for integrin alpha subunits. We conclude that sponges, the oldest multicellular animal phylum, already utilize the struct…