Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The surface protein composition of members of a serogroup of Aeromonas hydrophila which exhibit high virulence for fish was examined. Treatment of whole cells of representative strain A. hydrophila TF7 with 0.2 M glycine buffer (pH 4.0) resulted in the release of sheets of a tetragonal surface protein array. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis analysis showed that this sheet material was composed primarily of a protein of apparent molecular weight 52,000 (52K protein). A 52K protein was also the predominant protein in glycine extracts of other members of the high-virulence serogroup. Immunoblotting with antiserum raised against formalinized whole cells of A. hydrophila TF7 showed the 52K S-layer protein to be the major surface protein antigen, and impermeant Sulfo-NHS-Biotin cell surface labeling showed that the 52K S-layer protein was the only protein accessible to the Sulfo-NHS-Biotin label and effectively masked underlying outer membrane (OM) proteins. In its native surface conformation the 52K S-layer protein was only weakly reactive with a lactoperoxidase 125I surface iodination procedure. A UV-induced rough lipopolysaccharide (LPS) mutant of TF7 was found to produce an intact S layer, but a deep rough LPS mutant was unable to maintain an array on the cell surface and excreted the S-layer protein into the growth medium, indicating that a minimum LPS oligosaccharide size was required for A. hydrophila S-layer anchoring. The 52K S-layer protein exhibited hear-dependent SDS-solubilization behavior when associated with OM, but was fully solubilized at all temperatures after removal from the OM, indicating a strong interaction of the S layer with the underlying OM. The native S layer was permeable to 125I in the lactoperoxidase radiolabeling procedure, and two major OM proteins of molecular weights 30,000 and 48,000 were iodinated. The 48K species was a peptidoglycan-associated, transmembrane protein which exhibited heat-modifiable SDS solubilization behaviour characteristic of a porin protein. A 50K major peptidoglycan-associated OM protein which was not radiolabeled exhibited similar SDS heat modification characteristics and possibly represents a second porin protein.
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PMID:Surface protein composition of Aeromonas hydrophila strains virulent for fish: identification of a surface array protein. 327 60

Rabbit antibodies have been prepared against ERp61, ERp59, and ERp49, three protein components of rough endoplasmic reticulum (RER) purified from mineral oil-induced plasmacytoma 315 (MOPC-315) tissue. Analysis of subcellular fractions of MOPC-315 tissue by an immunoprecipitation procedure demonstrated that all three endoplasmic reticulum proteins (ERps) were most enriched in the RER. Immunologically cross-reacting proteins of similar molecular weight have been detected in other eucaryotic cell lines. We have used these antibodies to study the post-translational processing and biosynthetic sorting of the three ERps in pulse-labeled MOPC-315 cells. No larger precursor forms of the ERps were detected and none of the ERps were found to possess asparagine-linked oligosaccharide moieties. We have used a sucrose gradient analysis of pulse-labeled MOPC-315 cells to study the biosynthetic sorting of ERp61, ERp59 and ERp49 and have found no evidence to suggest that these proteins ever leave the endoplasmic reticulum. In addition, all three ERps appeared to have luminally exposed domains. ERp61 and ERp59 were entirely protected by the ER membrane in the absence of detergent, while ERp49 was a transmembrane protein that also possesses a cytoplasmically exposed domain. We have used the anti-ERp antibodies to quantitate the synthesis and accumulation of the three ERps during lipopolysaccharide (LPS)-induced lymphocyte differentiation. After 48 h of culture in the presence of LPS, the synthesis of ERp49 increased sixfold relative to that in control cells. The synthesis and membrane accumulation of ERp61 and ERp59 were less affected by the LPS treatment. Thus, membranes isolated from LPS-treated cells were enriched in ERp49 relative to those isolated from control cells.
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PMID:Structure and assembly of the endoplasmic reticulum: biosynthesis and intracellular sorting of ERp61, ERp59, and ERp49, three protein components of murine endoplasmic reticulum. 395 60

In humans and experimental animals the presence of bacterial lipopolysaccharide (endotoxin, LPS) signals the presence of gram-negative bacteria. Recognition of LPS triggers gene induction by myeloid and nonmyeloid lineage cells. These inducible genes encode proteins that include cytokines, adhesive proteins, and enzymes that produce low molecular weight proinflammatory mediators. Together the products of these inducible genes upregulate host defense systems that participate in eliminating the bacterial infection. Unfortunately, these same mediators contribute to a serious human disease known as septic shock. Considerable progress has been made during the past decade in determining the sources, identities, and sequence of release of these mediators. In contrast, until recently, marked gaps in our knowledge existed regarding the identity of the LPS receptor and intracellular signaling pathways responsible for LPS-induced cell activation. The discovery in 1986 of a plasma protein termed LPS binding protein (LBP) led to the discovery of unanticipated mechanisms of LPS-induced cell activation. CD14 was found as a soluble serum protein or as a glycosylphosphatidylinositol (GPI)-anchored protein of myeloid lineage cells; it now occupies a key role in LPS-induced cell activation as we understand it today. Here we discuss how LBP enables LPS binding to CD14 and how complexes of LPS and soluble or GPI-anchored CD14 participate in cell activation. We also review the evidence supporting a model for a functional LPS receptor of myeloid cells, which is multimeric, comprised of GPI-anchored CD14 and a presently unidentified transmembrane protein that together bind LPS and initiate cell activation via kinase cascades.
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PMID:Receptor-dependent mechanisms of cell stimulation by bacterial endotoxin. 754 10

The TNF family is involved in the regulation of the immune system, and its members have been implicated in a variety of biological events such as apoptosis, cell proliferation, differentiation and survival. Here we present a new member of the TNF family, tumor necrosis factor superfamily member 20 (TNFSF20) that we have identified from the expressed sequence tag (EST) database and characterized. The human protein is a 285 amino acid long type II transmembrane protein and is 19% homologous to TNF in its extra-cellular domain. TNFSF20 is expressed at the surface of antigen presenting cells such as cells of the macrophagemonocyte lineage and dendritic cells. After treatment with bacterial lipopolysaccharide (LPS), TNFSF20 expression is downregulated at the surface of the expresssing cells, suggesting that the membrane-bound protein gets cleaved, and that a soluble factor is released in the extra-cellular compartment. The soluble form of the recombinant TNFSF20 induces proliferation of resting peripheral blood monocytes (PBMC) and cell death of activated lymphocytes. TNFSF20 might therefore play a critical role in the regulation of cell-mediated immune responses.
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PMID:Characterization of a new member of the TNF family expressed on antigen presenting cells. 1066 73

Activated monocytes and macrophages secrete the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). TNF-alpha is produced as a 26 kd transmembrane protein that is cleaved to release a 17 kd soluble protein. TNF-alpha in both forms is biologically active. The intracellular trafficking of membrane-associated TNF-alpha in lipopolysaccharide-activated mouse macrophages was assessed after treatment with the metalloprotease inhibitor BB-3103, which prevents the cleavage of pro-TNF-alpha. Immunoprecipitation and immunofluorescence studies showed sustained expression of cell-associated TNF-alpha in the presence of the inhibitor. Cell immunoreactivity and surface biotinylation revealed that uncleaved TNF-alpha accumulated on the cell surface and was endocytosed, appearing in intracellular vesicles. Perturbation of post-Golgi traffic blocked the surface expression of 26 kd TNF-alpha. Tracking a bolus of TNF-alpha over time in cycloheximide-treated cells confirmed that uncleaved TNF-alpha is first transported to the cell surface and subsequently endocytosed. Vesicular structures immunoreactive for TNF-alpha were identified as endosomes by double labeling. The secretory and membrane-associated endocytic trafficking of TNF-alpha provides a mechanism for modulating the quantity of biologically active 26 kd TNF-alpha expressed on macrophages, allowing regulation of paracrine and autocrine responses.
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PMID:Endocytosis of uncleaved tumor necrosis factor-alpha in macrophages. 1120 69

The lipopolysaccharide (LPS)-binding protein (LBP) has a concentration-dependent dual role in the pathogenesis of gram-negative sepsis: low concentrations of LBP enhance the LPS-induced activation of mononuclear cells (MNC), whereas the acute-phase rise in LBP concentrations inhibits LPS-induced cellular stimulation. In stimulation experiments, we have found that LBP mediates the LPS-induced cytokine release from MNC even under serum-free conditions. In biophysical experiments we demonstrated that LBP binds and intercalates into lipid membranes, amplified by negative charges of the latter, and that intercalated LBP can mediate the CD14-independent intercalation of LPS into membranes in a lipid-specific and temperature-dependent manner. In contrast, prior complexation of LBP and LPS inhibited binding of these complexes to membranes due to different binding of LBP to LPS or phospholipids. This results in a neutralization of LPS and, therefore, to a reduced production of tumor necrosis factor by MNC. We propose that LBP is not only present as a soluble protein in the serum but may also be incorporated as a transmembrane protein in the cytoplasmic membrane of MNC and that the interaction of LPS with membrane-associated LBP may be an important step in LBP-mediated activation of MNC, whereas LBP-LPS complexation in the serum leads to a neutralization of LPS.
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PMID:Dual role of lipopolysaccharide (LPS)-binding protein in neutralization of LPS and enhancement of LPS-induced activation of mononuclear cells. 1159 69

We have cloned the mouse homologue of human Langerin (h-Langerin), a type II transmembrane protein with a single external C-type lectin domain. Mouse Langerin (m-Langerin) displays 65 and 74% homologies in total amino acid and lectin domains with those of h-Langerin. The cognate mouse and rat genes were assigned to chromosome 6D1-D2 and chromosome 4q33 distal-q34.1 proximal respectively, syntenic to the h-Langerin gene on chromosome 2p13. With RT-PCR, m-Langerin transcripts were as expected detected in MHC class II+, but not MHC class II-, cells from epidermis and the expression level was reduced by culture. However, m-Langerin transcripts were also expressed in spleen, lymph nodes (LN), thymus, liver, lung and even heart, but not gut-associated lymphoid tissues. In single-cell lymphoid suspensions, m-Langerin transcripts were mainly detected in the CD11c+ dendritic cells (DC), especially the CD11blow/CD8high fraction of spleen and LN. DC generated from bone marrow precursors by granulocyte macrophage colony stimulating factor (GM-CSF) expressed m-Langerin, but this was shut down during maturation with CD40 ligand or lipopolysaccharide. DC derived from blood monocytes by GM-CSF + IL-4 lacked m-Langerin unless the cultures were supplemented with transforming growth factor (TGF)-beta1. Unexpectedly, significant amounts of m-Langerin transcripts were detected in skin and LN of TGF-beta1-deficient mice, although in much lower amounts than littermate controls. Recombinant m-Langerin could form multimers and bind to mannan-agarose. These findings indicate that Langerin expression is regulated at several levels: by TGF-beta1, DC subsets, DC maturation and the tissue environment.
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PMID:Identification and expression of mouse Langerin (CD207) in dendritic cells. 1197 73

MARCO is a type II transmembrane protein of the class A scavenger receptor family. It has a short N-terminal cytoplasmic domain, a transmembrane domain, and a large extracellular part composed of a 75-residue long spacer domain, a 270-residue collagenous domain, and a 99-residue long scavenger receptor cysteine-rich (SRCR) domain. Previous studies have indicated a role for this receptor in anti-microbial host defense functions. In this work we have produced the extracellular part of MARCO as a recombinant protein, and analyzed its binding properties. The production of this protein, soluble MARCO (sMARCO), has made it possible for the first time to study MARCO and its binding properties in a cell-free system. Using circular dichroism analyses, a protease-sensitive assay, and rotary shadowing electron microscopy, sMARCO was shown to have a triple-helical collagenous structure. Rotary shadowing also demonstrated that the molecules often associate with each other via the globes. sMARCO was found to bind avidly both heat-killed and living bacteria. Lipopolysaccharide, an important component of the outer membrane of Gram-negative bacteria, was shown to be a ligand of MARCO. Studies with different bacterial strains indicated that the O-side chain of lipopolysaccharide is not needed for the bacterial recognition. Finally, the C-terminal SRCR domain was also produced as a recombinant protein, and its bacteria-binding capability was studied. Although the transfection experiments with transmembrane MARCO variants have indicated a crucial role for this domain in bacterial binding, the monomeric domain exhibited low, barely detectable bacteria-binding activity. Thus, it is possible that cooperation between the SRCR domain and the collagenous domain is needed for high-affinity bacterial binding, or that the SRCR domain has to be in a trimeric form to effectively bind to bacteria.
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PMID:Characterization of recombinant soluble macrophage scavenger receptor MARCO. 1209 27

The outer membrane (OM) of the mammalian pathogen Leptospira kirschneri was isolated in the form of membrane vesicles by alkaline plasmolysis and separated from the protoplasmic cylinder by sucrose density gradient ultracentrifugation. All four components of the alkaline plasmolysis buffer, including 1.0 M NaCl, 27% sucrose (wt/vol), 2 mM EDTA, and 10 mM Tris (pH 9), were required for efficient OM release, as judged by recovery of leptospiral lipopolysaccharide. Two populations of OM vesicles (OMVs) were recovered, with peak concentrations found in the sucrose gradient at densities of 1.16 and 1.18 g/ml. Transmission electron microscopy revealed that the more buoyant OMV population was smaller (<0.1 micro m in diameter) than the denser OMV population (0.2 to 0.3 micro m in diameter). The densities of both populations of OMVs were distinct from that of the protoplasmic-cylinder material, which was found in the sucrose gradient at a density of 1.20 g/ml. The OMV fractions were free of protoplasmic-cylinder material, as judged by immunoblotting with antibodies to the endoflagellar sheath protein, heat shock protein GroEL, and two novel cytoplasmic membrane proteins, lipoprotein LipL31 and transmembrane protein ImpL63. The protein components of the OMVs were characterized by one- and two-dimensional immunoblotting and found to include previously described OM proteins (OMPs), including the porin OmpL1; the lipoproteins LipL32, LipL36, and LipL41; and the peripheral membrane protein P31(LipL45). A number of less well-characterized OMPs were also identified, including those with molecular masses of 16, 21, 21.5, 22, 31, 36, 44, 48, 90, and 116 kDa. The 48-kDa OMP was identified as a novel OM lipoprotein designated LipL48. The use of membrane-specific markers in OM isolation techniques facilitates an accurate description of the leptospiral OM and its components.
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PMID:Characterization of the leptospiral outer membrane and description of three novel leptospiral membrane proteins. 1218 39

Inflammatory responses during sepsis are determined by leucocyte recruitment into inflamed tissues. Both chemokines and adhesion molecules are believed to be involved in this process. As fractalkine exists as transmembrane protein with cell adhesion properties and as soluble chemotactic factor, the present study was conducted to study the role of fractalkine, produced by microvascular and macrovascular endothelial cells, in neutrophil recruitment. Lung microvascular endothelial cells (LMVECs) stimulated with lipopolysaccharide, tumour necrosis factor-alpha or interleukin-1 (IL-1) produced much more fractalkine compared with the macrovascular human umbilical vein endothelial cells (HUVECs). No differences were found between microvascular endothelial cells of different organs. Chemotactic activity in supernatants was significantly stronger in stimulated LMVEC when compared with HUVEC. Although recombinant fractalkine induced migration of neutrophils, IL-8 and monocyte chemoattractant protein-1 were found to be more strictly required. In vivo fractalkine was strongly upregulated in septic lung and kidney. Our data suggest that fractalkine production per se does not explain the preference for inflammation in the lung of septic patients.
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PMID:Fractalkine is not a major chemoattractant for the migration of neutrophils across microvascular endothelium. 1286 39


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