Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O95477 (membrane-bound)
 29,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The immunochemical and immunocytochemical reactivity of an anti-carbohydrate monoclonal antibody (Elec-39), obtained against acetylcholinesterase from Electrophorus electricus electric organ, was followed during the postnatal development of the rat cerebellum. The specificity of this antibody resembles that of a family of anti-carbohydrate antibodies that includes HNK-1, L2, NC-1 and NSP-4, as well as IgMs that occur in some human neuropathies. As revealed by immunoblotting techniques, the reactivity of Elec-39 is maximum around postnatal days 10-12. At this age, the antibody reveals eight major proteins of mol. wt ranging between 14 and 150 kDa. Some of them (with mol. wts of 14, 18, 28 and 31 kDa) are transiently expressed. They correspond to previously identified glycoproteins binding to the plant lectin concanavalin A and binding also to the endogenous mannose-binding lectin CSL and endogenous membrane-bound mannose-binding lectin. In young animals, an important staining with the Elec-39 antibody can be observed on postmitotic precursors of granule cells, on astrocyte processes in the external granular layer, on newly formed parallel fibres and on unmyelinated axons of the white matter. In adult animals, the labelling is localized essentially in myelin and also in the cytoplasm of astrocytes. These results are discussed in relation to ontogenetic phenomena occurring during cerebellar development and the potential role of the carbohydrate epitope revealed with Elec-39 as a determinant in cell adhesion processes.
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PMID:Expression and localization in the developing cerebellum of the carbohydrate epitopes revealed by Elec-39, an IgM monoclonal antibody related to HNK-1. 171 52

Immunochemical localization of an endogenous mannose-binding protein, the cerebellar soluble lectin (CSL; Zanetta et al., J. Neurochem. 49, 1250-1257 (1987)), in Chinese hamster ovary cells indicated its high concentration in areas of contact between cells. This suggested its role in cell adhesion. The pattern of staining differed significantly in the cells cultured in suspension from that grown as monolayer. In cells maintained for a short time as suspension, the extracellular CSL immunoreactivity was found mainly in close apposition to the plasma membrane including contact areas. In cells cultured as monolayer, extracellularly, the lectin was found both at the cell surface and in a 75-nm thick layer between two cells, apparently adhering to the cell surface through bridges. Endogenous glycoprotein ligands of CSL were present in the cultures of CHO cells, both as membrane-bound glycoproteins and as glycoprotein ligands soluble in the presence of mannose in the absence of detergent. The lectin CSL induced adhesion between these cells as evident by low concentration of anti-CSL Fab fragments inhibiting such adhesion. These data suggested that adhesion between CHO cells occurs, in part, through a glycobiological recognition system involving CSL. This mechanism should be taken into account for the interpretation of experiments of transfection in CHO cells of the genes of glycoproteins involved in cell adhesion.
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PMID:Involvement of the endogenous lectin CSL in adhesion of Chinese hamster ovary cells. 180 25

A soluble (cell-free) oncofetal antigen (OFA) was detected in murine and human amniotic fluids by immunostaining with the murine monoclonal antibody (MAb 115) produced by syngeneic immunization with mid-gestational mouse fetal cells. OFA was purified from the amniotic fluids by ammonium sulfate precipitation at 30-70% saturation, followed by successive gel chromatography of the OFA-containing fraction on Sephacryl-S300 HR, Q- and S-Sepharoses and lentil lectin agarose. The fraction eluted from the lentil lectin column gave a single band on SDS-PAGE of the same molecular weight as the membrane-bound OFA found on both fetal and tumor tissues of humans and several rodents. Both soluble and membrane-bound OFAs share several chemical characteristics, including binding to lentil lectin and wheat-germ agglutinin, molecular weight (44 kDa) and pI (6.8). Mild periodate oxidation of OFA did not affect its binding to MAb 115 in an enzyme-linked immunosorbent assay, indicating that the reactive epitope is a peptide.
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PMID:Isolation and partial characterization of a soluble oncofetal antigen from murine and human amniotic fluids. 185 Mar 86

Neuroendocrine carcinoma of the skin usually occurs in elderly individuals. Head and neck are the most common primary sites followed by the extremities and trunk. As this tumor represents a remarkable rarity in younger people, we report the case of a 33-year-old woman with a neuroendocrine carcinoma in an unusual localization. Diagnosis was based on the results of the examination of a metastasis in the inguinal lymph nodes. The lesion at the Labium minus pudendi which is to be considered the primary tumor was detected several months later. Diagnosis of Merkel cell tumor until recently had depended on ultrastructural demonstration of dense-core membrane-bound granules. Today, diagnosis can be secured also by optical light microscopy, on the basis of a certain constellation of immunohistochemical and lectin histochemical findings.
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PMID:[Merkel cell tumor (neuroendocrine carcinoma of the skin) in an unusual location. Immunohistochemical and lectin histochemical findings]. 191 29

Somatostatin receptors were solubilized from rat pancreatic membranes with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonic acid (CHAPS). The binding of an iodinated somatostatin analog [125I-Tyr3]SMS to the soluble fraction was time-dependent, saturable, and reversible. Scatchard analysis of equilibrium binding data indicated that the soluble extract contained a single class of somatostatin binding sites with a Kd of 0.3 nM and a Bmax of 210 fmol/mg. As observed with membrane-bound receptors, soluble binding receptors were sensitive to the GTP analog GTP gamma S indicating that they are functionally linked to a G protein. A molecular weight of about 400,000 was determined for soluble receptors under native conditions by gel filtration. In denaturing gel electrophoresis, photoaffinity labeling of soluble receptors identified a major protein of Mr = 100,000 and two minor proteins of Mr = 56,000 and 21,000. Isoelectric focusing of soluble receptors revealed that the somatostatin receptor is an acidic protein with pI 4.8. The soluble somatostatin receptor is a glycoprotein which can be specifically bound to the wheat germ agglutinin lectin and eluted by triacetyl-chitotriose.
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PMID:Solubilization and characterization of active somatostatin receptors from rat pancreas. 196 49

The recognition of hemopoietic stem cell after intravenous transplantation of marrow cells occurs initially by a lectin moiety on the surface of marrow sinus endothelium. The cell is then transported across the endothelial cytoplasm much in the way that a soluble ligand, such as transferrin, is transported. In the extravascular compartment, the cell binds to lineage-specific stromal cells. This mechanism, known as homing, is mediated by a lectin-glycoconjugate interaction, the lectin being on the surface of progenitor cell with specificity for galactosyl and mannosyl residues. The binding is subsequently stabilized by membrane-bound proteoglycans, integrin-like receptors, and fibronectin.
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PMID:Homing of hemopoietic progenitor cells to the marrow. 200 37

Previously, we showed using electron paramagnetic resonance that the physical state of one side of erythrocyte membranes could be modulated by agents which interact with the opposite side (reviewed in Butterfield, 1989, Biological and Synthetic Membranes, A. R. Liss, Inc., New York). The present study was undertaken to determine whether membrane-bound enzymes would exhibit a similar transmembrane modulation effect. The effects of known, domain-specific modulators of the physical state of erythrocyte membranes on the activity of two membrane-bound enzymes were investigated. Acetylcholinesterase, an enzyme having its active site situated on the extracellular side of the membrane, seemed to be unaffected by most of the modulators employed in this study, with the exception of reversible inhibition by benzyl alcohol. Conversely, the activity of NADH:cytochrome b5 reductase, an enzyme whose active site is located on the cytoplasmic side of the erythrocyte membrane, was increased by those agents that interact primarily with skeletal proteins to increase skeletal protein-protein interactions; however, those agents which interact primarily with the skeleton to decrease protein-protein interactions decreased the activity of NADH:cytochrome b5 reductase. This enzyme's activity was also significantly altered by lectins which bind specifically to the external face of glycophorin A on the opposite side of the membrane, but it's activity was unaffected by concanavalin A, a lectin which binds to the external face of band 3. The results of these biochemical studies suggested that NADH:cytochrome b5 reductase can interact with and its activity can be modulated by skeletal or transmembrane proteins. In addition, these results support the hypothesis that in transmembrane signaling processes, biophysical and biochemical changes are correlated.
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PMID:Effects of domain-specific erythrocyte membrane modulators on acetylcholinesterase and NADH:cytochrome b5 reductase activities. 216 52

Heparin and related polyanions are a new class of compounds interacting with 1,4-dihydropyridine-sensitive L-type Ca2+ channels in a tissue-specific manner. Labeling of membrane-bound Ca2+ channels in rabbit skeletal muscle transverse tubules at the phenylalkylamine, benzothiazepine, and 1,4-dihydropyridine-selective domains was inhibited reversibly by a noncompetitive mechanism as shown by equilibrium saturation analysis and kinetic studies. (+)-cis-diltiazem but not (-)-cis-diltiazem reduced the inhibitory potency of heparin for 1,4-dihydropyridines. Antagonistic but not agonistic 1,4-dihydropyridines reversed heparin inhibition at the benzothiazepine site. Heparin forms a tight complex with the purified Ca2+ channel which is highly sensitive with respect to heparin inhibition (IC50 value: 0.05 microgram/ml) of 1,4-dihydropyridine binding. Reconstituted channel complexes have completely lost 1,4-dihydropyridine binding-inhibition by heparin and are not retained by lectin or heparin affinity columns. In whole cell patch clamp experiments with guinea-pig cardiac myocytes heparin increased the current through L-type Ca2+ channels when applied extracellulary. Synthetic peptides (representing putative heparin binding domains) which were derived from the rabbit skeletal muscle alpha 1-subunit reversed the inhibitory effects of heparin on 1,4-dihydropyridine receptors. Reversal for a peptide representing an extracellular domain occurred by an apparently competitive mechanism. It is suggested that heparin and related polyanions may interact with an evolutionary conserved cluster of basic amino acids in the large putative extracellular domain connecting the fifth and sixth putative transmembrane segment in the first motif of the ionic pore-forming alpha 1-subunit from skeletal muscle.
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PMID:Heparin binds with high affinity to voltage-dependent L-type Ca2+ channels. Evidence for an agonistic action. 216 34

A peculiar case of astrocytoma showing a histological appearance similar to granular cell tumor was reported. The tumor consisted of large round cells containing numerous intracytoplasmic eosinophilic granules, partially intermingled with atypical astrocytes, and part of it showed a transition to distinct areas of fibrillary astrocytoma. The granules were periodic acid-Schiff-positive (with resistance to diastase digestion), negative for fat stains and revealed lectin-binding patterns similar to those in granular cell tumor. Ultrastructurally the granules were partially membrane-bound, dense bodies compatible with secondary lysosomes. It was suggested that the granular cells were of astrocytic origin because of their immunoreactivity for glial fibrillary acidic protein (GFAP) and ultrastructural observation of intermediate filaments corresponding to GFAP.
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PMID:Astrocytoma with granular cell tumor-like changes. Report of a case with histochemical and ultrastructural characterization of granular cells. 216 87

In the central nervous system, postmitotic neurons migrate along astrocytic processes to reach their adult position. The molecular mechanisms of this guided migration are not clearly defined, although some steps have been shown to involve proteases and cell adhesion molecules. We report that monovalent antibodies (Fab fragments) raised against an endogenous cerebellar soluble lectin (CSL) completely inhibit neuronal migration in cultures of cerebellar explants at concentrations as low as 50 micrograms/ml. A similar inhibition pattern was obtained with Fab fragments prepared against one of the endogenous glycoprotein ligands of CSL, the 31-kDa glycoprotein (this glycoprotein is a membrane-bound glycoprotein specifically occurring, in the cerebellum, at the surface of immature neurons). We propose that this lectin-glycoprotein interaction supports the adhesion between neurons and the astrocyte guide during the migration of cerebellar immature neurons.
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PMID:An endogenous lectin and one of its neuronal glycoprotein ligands are involved in contact guidance of neuron migration. 220 Oct 31


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