Search results for "Cell Surface"
showing 10 items of 201 documents
Nimrod, a Putative Phagocytosis Receptor with EGF Repeats in Drosophila Plasmatocytes
2007
SummaryThe hemocytes, the blood cells of Drosophila, participate in the humoral and cellular immune defense reactions against microbes and parasites [1–8]. The plasmatocytes, one class of hemocytes, are phagocytically active and play an important role in immunity and development by removing microorganisms as well as apoptotic cells. On the surface of circulating and sessile plasmatocytes, we have now identified a protein, Nimrod C1 (NimC1), which is involved in the phagocytosis of bacteria. Suppression of NimC1 expression in plasmatocytes inhibited the phagocytosis of Staphylococcus aureus. Conversely, overexpression of NimC1 in S2 cells stimulated the phagocytosis of both S. aureus and Esc…
Molecular mechanisms determining the strength of receptor-mediated intermembrane adhesion
1995
The strength of receptor-mediated cell adhesion is directly controlled by the mechanism of cohesive failure between the cell surface and underlying substrate. Unbinding can occur either at the locus of the specific bond or within the bilayer, which results in tearing the hydrophobic anchors from the membrane interior. In this work, the surface force apparatus has been used to investigate the relationship between the receptor-ligand bond affinities and the dominant mechanism of receptor-coupled membrane detachment. The receptors and ligands used in this study were membrane-bound streptavidin and biotin analogs, respectively, with solution affinities ranging over 10 orders of magnitude. With …
Evidence for a multistep mechanism for cell-cell fusion by herpes simplex virus with mutations in the syn 3 locus using heparin derivatives during fu…
1994
Addition of heparin-Na+ as well as related substances of high and intermediate MW (Arteparon and polyanion SP54) 3 h after infection inhibit fusion from within (FFWI) induced by HSV strains with mutations in the syn 3 locus only. The concentration of heparin-Na+ required to inhibit FFWI is 10-fold higher (1 mg/ml) than that needed to inhibit adsorption. Instead of fusion, cell rounding is observed. The effect is readily reversible. A low MW heparin disaccharide is ineffective. Neomycin, at a concentration of 8 mM, inhibits FFWI induced by all HSV-1 but not HSV-2 strains, whereas adsorption is inhibited at 3 mM. We conclude from our observations that cell-cell fusion (FFWI) induced by syn 3 …
Role of tir and intimin in the virulence of rabbit enteropathogenic Escherichia coli serotype O103:H2.
2000
ABSTRACT Attaching and effacing (A/E) rabbit enteropathogenic Escherichia coli (REPEC) strains belonging to serogroup O103 are an important cause of diarrhea in weaned rabbits. Like human EPEC strains, they possess the locus of enterocyte effacement clustering the genes involved in the formation of the A/E lesions. In addition, pathogenic REPEC O103 strains produce an Esp-dependent but Eae (intimin)-independent alteration of the host cell cytoskeleton characterized by the formation of focal adhesion complexes and the reorganization of the actin cytoskeleton into bundles of stress fibers. To investigate the role of intimin and its translocated coreceptor (Tir) in the pathogenicity of REPEC, …
Lactococcal 949 group phages recognize a carbohydrate receptor on the host cell surface
2015
ABSTRACT Lactococcal bacteriophages represent one of the leading causes of dairy fermentation failure and product inconsistencies. A new member of the lactococcal 949 phage group, named WRP3, was isolated from cheese whey from a Sicilian factory in 2011. The genome sequence of this phage was determined, and it constitutes the largest lactococcal phage genome currently known, at 130,008 bp. Detailed bioinformatic analysis of the genomic region encoding the presumed initiator complex and baseplate of WRP3 has aided in the functional assignment of several open reading frames (ORFs), particularly that for the receptor binding protein required for host recognition. Furthermore, we demonstrate th…
Yeast Killer Toxin-Like Candidacidal Ab6 Antibodies Elicited through the Manipulation of the Idiotypic Cascade
2014
A mouse anti-anti-anti-idiotypic (Id) IgM monoclonal antibody (mAb K20, Ab4), functionally mimicking a Wyckerhamomyces anomalus (Pichia anomala) killer toxin (KT) characterized by fungicidal activity against yeasts presenting specific cell wall receptors (KTR) mainly constituted by β-1,3-glucan, was produced from animals presenting anti-KT Abs (Ab3) following immunization with a rat IgM anti-Id KT-like mAb (mAb K10, Ab2). MAb K10 was produced by immunization with a KT-neutralizing mAb (mAb KT4, Ab1) bearing the internal image of KTR. MAb K20, likewise mAb K10, proved to be fungicidal in vitro against KT-sensitive Candida albicans cells, an activity neutralized by mAb KT4, and was capable of…
Neural activities of IL-6-type cytokines often depend on soluble cytokine receptors
1999
Cytokines of the interleukin-6 (IL-6) family participate in regulatory and inflammatory processes within the nervous system. IL-6, ciliary neurotrophic factor (CNTF) and IL-11 act via specific membrane receptors which, together with their ligands, associate with signal-transducing receptor subunits thereby initiating cytoplasmic signalling. Cells which only express signal-transducing receptor subunits but no ligand binding subunits for IL-6, CNTF and IL-11 are refractory to these cytokines. An unusual feature of the IL-6 cytokine family is that the soluble forms of the ligand binding receptor subunits generated by one cell type in complex with their ligands can directly stimulate the signal…
Sponge aggregation factor: identification of the specific collagen-binding site by means of a monoclonal antibody.
1988
The aggregation factor (AF) from the sponge Geodia cydonium is known to be a complex proteinaceous particle, composed of a series of different (glyco)proteins (Mr lower than 150,000) around a 90S sunburst-like core structure. One of the low-Mr proteins is the 47-KD cell binding fragment. We describe a new monoclonal antibody (mAb), III1E6, raised against purified AF particles, which recognizes in tissue slices structures present both on the plasma membrane and in a network-like manner in the extracellular space. By applying immunoelectron microscopical, immunoblotting, and immunoaffinity chromatographical techniques, the mAb III1E6 was shown to recognize the core structure of the AF partic…
Formation and function of a complement-activating enzyme generated from factors of guinea pig serum and cobra venom
1971
An enzymatic complex can be formed by factors from guinea pig serum and cobra venom, which is able to activate C3 bypassing C1, C4 and C2. Formation and action of the enzyme are described. The action on C3 results in an activation of the terminal complement components and in membrane destruction provided suitable membrane receptors are available.
The hedgehog receptor patched is involved in cholesterol transport.
2011
International audience; BACKGROUND: Sonic hedgehog (Shh) signaling plays a crucial role in growth and patterning during embryonic development, and also in stem cell maintenance and tissue regeneration in adults. Aberrant Shh pathway activation is involved in the development of many tumors, and one of the most affected Shh signaling steps found in these tumors is the regulation of the signaling receptor Smoothened by the Shh receptor Patched. In the present work, we investigated Patched activity and the mechanism by which Patched inhibits Smoothened. METHODOLOGY/PRINCIPAL FINDINGS: Using the well-known Shh-responding cell line of mouse fibroblasts NIH 3T3, we first observed that enhancement …