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At least 289 records · Page 16Linked to original sources

PubMed1975

A lipid-linked oligosaccharide intermediate in glycoprotein synthesis. Characterization of [Man-14C]glycoproteins labeled from [Man-14C]oligosaccharide-lipid and GDP-[14C]Man.

Endogenous proteins of cell-free preparations of hen oviduct labeled from GDP-[14C]Man or from [Man-14C]oligosaccharide-lipid have been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Under the conditions tested, a polypeptide chain of molecular weight about 25,000 was the principle acceptor for the oligosaccharide moiety of exogenous [Man-14C]oligosaccharide-lipid. The product labeled by [Man-14C]oligosaccharide-lipid appeared identical with one of three glycoproteins formed when GDP-[14C]Man was incubated with a crude membrane fraction. These three proteins (apparent molecular weight of 75,000, 55,000, and 25,000) accounted for nearly two-thirds of the [14C]mannose-labeled glycoprotein products using GDP-[14C]Man and either the crude membrane fraction or a total oviduct homogenate. Thus, all of the mannose acceptor proteins present in the oviduct homogenate appear to be membrane-bound. Analyses of the [Man-14C]glycoproteins labeled from GDP-[14C]Man in membrane fractions from hen kidney, liver, brain, and oviduct indicated that a labeled polypeptide of apparent molecular weight 25,000 was the only major protein product common to the four preparations.

Animals↗

PubMed1990

Molecular mimicry: a herpes virus glycoprotein antigenically related to a cell-surface glycoprotein expressed by macrophages, polymorphonuclear leucocytes, and platelets.

Bovine herpes virus type 1 (BHV-1) gIII is a major virion glycoprotein with homology to the immunoglobulin superfamily. We have investigated the possibility that gIII is related to host molecules and have identified a gIII-specific monoclonal antibody (mAb) that cross-reacts with normal bovine cells. The cross-reactive entity was expressed mainly on monocyte/macrophages (M phi), polymorphonuclear leucocytes (PMN) and platelets, and was identified as a 43,000-63,000 molecular weight (MW) cell-surface glycoprotein. For M phi, the glycoprotein appears to be a general lineage marker, rather than a maturation or activation marker, and may be a functional receptor, as evidenced by its endocytosis via coated pits and its involvement in proliferation of mononuclear cells in vitro. This novel leucocyte marker was also detected on subsets of human, ovine and canine M phi. Competitive binding assays with sera from cattle immunized with BHV-1 or gIII revealed apparent low responsiveness to the cross-reactive epitope. The results suggest that BHV-1 gIII is antigenically related to a novel host leucocyte receptor and that evasion and/or interference with leucocyte function may be a consequence of this molecular mimicry relationship.

Animals↗

PubMed1991

Isolation of four major glycoprotein families (ZP1, ZP2, ZP3, ZP4) of porcine zona pellucida and characterization of antisera raised to each glycoprotein family.

Porcine zona pellucida (ZP) contains antigens which cross-react with man, and anti porcine ZP antibody was found to exhibit a strong blocking effect on human sperm-ZP interaction. Previously, we found that porcine ZP was composed of four major glycoprotein families (ZP1, ZP2, ZP3, ZP4). In this study, each of the glycoprotein families was isolated by O'Farrell's two-dimensional electrophoresis and injected into mice to obtain antisera to each component. All the mouse antisera had high titers of antibodies to porcine and human ZP in an immunofluorescent staining test. Western blot analysis showed that although the antisera most strongly reacted with the corresponding components of porcine ZP, each glycoprotein family also possessed antigens which cross-reacted with each other. The antisera to ZP1, ZP3 and ZP4 strongly inhibited human sperm-ZP interaction but antiserum to ZP2 had no inhibitory effect on it.

Animals↗

PubMed1990

Rapid purification and characterization of human platelet glycoprotein V: the amino acid sequence contains leucine-rich repetitive modules as in glycoprotein Ib.

Glycoprotein V (GPV) is a membrane-associated, 82 Kd platelet glycoprotein that is hydrolyzed during thrombin activation to yield 69 Kd fragment. We have developed a rapid and simple method for isolation of the protein from platelet extracts using a combination of gel permeation, anion-exchange, and lectin affinity chromatography. The partial amino acid sequence was determined by analysis of peptides generated by digestion of the S-carboxyamido-methylated protein with Achromobacter protease I or cyanogen bromide. The sequence shows a remarkable periodicity of leucine residues, which is homologous to the consensus sequence of a highly diversified protein super-family with a common repetitive module. Thrombin cleavage site was determined to be located at the C-terminal region of GPV by analysis of the products separated by sizing and reversed-phase high performance liquid chromatography. By lectin blot analysis, the existence of mucin-type carbohydrate chains was indicated, as well as the existence of asparagine-linked carbohydrate chains shown by the amino acid sequence analysis. From these data, we report a structural model of GPV that is analogous to glycoprotein Ib.

Amino Acid Sequence↗

PubMed1987

[Immunochemical and physico-chemical characteristics of glycoprotein from retroplacental blood having several common antigenic determinants with trophoblastic beta 1-glycoprotein].

A glycoprotein (TSG-fs) isolated from retroplacental blood is shown to have common antigenic determinants with trophoblast-specific beta 1-glycoprotein (TSG, SP-1). Antigenic activity of TSG-fs constitute 3.4% of TSG's activity. Like TSG, glycoprotein TSG-fs contains four intramolecular disulfide bonds and belongs to proteins with predominantly beta-structure. CD-spectroscopy data give evidence of high stability of the secondary structure of TSG-fs. Immunochemical identity of TSG-fs with the reduced and carboxymethylated derivative of TSG has been demonstrated. The above data allow to suggest that TSG-fs is a fragment of the TSG molecule.

Amino Acids↗

PubMed1987

Proliferative and cytotoxic T cells to AIDS virus glycoproteins in chimpanzees immunized with a recombinant vaccinia virus expressing AIDS virus envelope glycoproteins.

PBL from chimpanzees immunized with a recombinant vaccinia virus that expresses HIV envelope glycoproteins ("env"), were found to proliferate after stimulation with HIV or with "env". Furthermore, CTL clones lytic for autologous target cells expressing HIV envelope glycoproteins were generated after stimulation of the chimpanzees' PBL with "env", indicating that immunization of these primates with a recombinant vaccinia virus primes HIV-specific CTL and also that HIV envelope glycoproteins serve as target antigens for CTL.

Animals↗

PubMed1985

The effect on pregnancy of intrauterine administration of antibodies against two pregnancy-associated murine proteins: murine pregnancy-specific beta 1-glycoprotein and murine pregnancy-associated alpha 2-glycoprotein.

Intrauterine administration of 100 arbitrary units (AU) of purified monospecific rabbit anti murine pregnancy specific beta 1-glycoprotein antibodies resulted in the loss of the fetuses in pregnant mice (14 out of 14). By contrast, a similar treatment with 100 AU of rabbit anti murine pregnancy-associated alpha 2-glycoprotein had an effect similar to saline on the outcome of pregnancy. Intravenous administration of 1000 AU of rabbit anti murine pregnancy specific beta 1-glycoprotein during pregnancy in mice had no effect on the outcome of pregnancy.

Animals↗

PubMed1985

The effect of glycoprotein-processing inhibitors on fucosylation of glycoproteins.

The influenza viral hemagglutinin contains L-fucose linked alpha 1,6 to some of the innermost GlcNAc residues of the complex oligosaccharides. In order to determine what structural features of the oligosaccharide were required for fucosylation or where in the processing pathway fucosylation occurred, influenza virus-infected MDCK cells were incubated in the presence of various inhibitors of glycoprotein processing to stop trimming at different points. After several hours of incubation with the inhibitors, [5,6-3H]fucose and [1-14C]mannose were added to label the glycoproteins, and cells were incubated in inhibitor and isotope for about 40 h to produce mature virus. Glycopeptides were prepared from the viral and the cellular glycoproteins, and these glycopeptides were isolated by gel filtration on Bio-Gel P-4. The glycopeptides were then digested with endo-beta-N-acetylglucosaminidase H and rechromatographed on the Bio-Gel column. In the presence of castanospermine or 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine, both inhibitors of glucosidase I, most of the radioactive mannose was found in Glc3Man7-9GlcNAc structures, and these did not contain radioactive fucose. In the presence of deoxymannojirimycin, an inhibitor of mannosidase I, most of the [14C]mannose was in a Man9GlcNAc structure which was also not fucosylated. However, in the presence of swainsonine, an inhibitor of mannosidase II, the [14C]mannose was mostly in hybrid types of oligosaccharides, and these structures also contained radioactive fucose. Treatment of the hybrid structures with endoglucosaminidase H released the [3H]fucose as a small peptide (Fuc-GlcNAc-peptide), whereas the [14C]mannose remained with the oligosaccharide. The data support the conclusion that the addition of fucose linked alpha 1,6 to the asparagine-linked GlcNAc is dependent upon the presence of a beta 1,2-GlcNAc residue on the alpha 1,3-mannose branch of the core structure.

Alkaloids↗

PubMed1982

Unique cell surface glycoprotein expression in hairy cell leukemia: effect of phorbol ester tumor promoters on surface glycoproteins, cell morphology, and adherence.

Hairy cell leukemia cells from eight different patients exhibited a characteristic cell surface glycoprotein pattern when labeled by the neuraminidase-galactose oxidase-NaB3H4 procedure. The diffuse high-molecular-weight glycoprotein band (Mr 230,000 to 300,000) was not seen in other leukemic cell types and may represent a specific hairy cell leukemia antigen. Hairy cell leukemia cells can be maintained as cell suspension cultures, but treatment with a variety of tumor-promoting phorbol esters caused the cells to adhere to plates, assume a fibroblastic elongated shape, and extend long processes. This dramatic morphological change was not associated with any change in surface glycoproteins.

Adult↗

PubMed1988

Galactose at the nonreducing terminus of O-linked oligosaccharides of mouse egg zona pellucida glycoprotein ZP3 is essential for the glycoprotein's sperm receptor activity.

During fertilization in mice, zona pellucida glycoprotein ZP3 mediates initial sperm-egg interactions by serving as receptor for sperm. Purified egg ZP3, as well as ZP3-derived O-linked oligosaccharides, exhibit sperm receptor activity in vitro. We report that treatment of purified egg ZP3 and ZP3-derived O-linked oligosaccharides with either alpha-galactosidase or galactose oxidase results in loss of sperm receptor activity. In the latter case, sperm receptor activity can be restored to the oxidized glycoprotein and O-linked oligosaccharides by treatment with sodium borohydride. We conclude that galactose, located in alpha-linkage at the nonreducing terminus of O-linked oligosaccharides, is at least one of the sugar determinants on ZP3 responsible for binding of sperm to the zona pellucida.

Animals↗

PubMed1988

Endocytosis of N-acetylglucosamine-containing glycoproteins by rat fibroblasts expressing a single species of chicken liver glycoprotein receptor.

A cDNA clone for the chicken liver receptor which mediates endocytosis of glycoproteins containing terminal N-acetylglucosamine has been isolated and sequenced, confirming the previously obtained amino acid sequence of this protein (which is also known as the chicken hepatic lectin). This cDNA was introduced into Rat-1 fibroblasts and expressed using the promotor in the long terminal repeat of Moloney murine leukemia virus. Cells expressing chicken receptor were identified by screening with antireceptor antibodies followed by fluorescein-conjugated second antibodies. Receptor expressed in these cells was indistinguishable on gel electrophoresis from receptor isolated from liver. Three clonally isolated lines were examined for their ability to bind agalacto-alpha 1-acid glycoproteins at 0 degrees C and to take up and degrade this ligand at 37 degrees C. The receptor number (50,000/cell), affinity for ligand (35 nM), and uptake rate (5 molecules ligand/surface receptor/h) are similar to those previously observed for chicken hepatocytes, and for the uptake of asialoglycoproteins by rat hepatocytes and hepatoma cells. These findings indicate that the chicken receptor correctly traverses the endocytic pathway in a rat cell even though the cytoplasmic domain of this protein shows no primary structural homology with the corresponding portion of the rat liver receptor or with receptors found in fibroblasts.

Acetylglucosamine↗

PubMed2002

The requirement of varicella zoster virus glycoprotein E (gE) for viral replication and effects of glycoprotein I on gE in melanoma cells.

The glycoprotein E (gE) of varicella zoster virus (VZV), encoded by ORF68, is the most abundant viral glycoprotein. In the current experiments, we demonstrated that ORF68 deletion was incompatible with recovery of infectious virus from VZV cosmids. Replacing ORF68 at a nonnative AvrII site in the genome restored infectivity. Further, we found that VZV gE could be expressed under the control of the Tet-On promoter in stably transfected melanoma cell lines (Met-gE cells) without evidence of toxicity. In these Met-gE cells, gE colocalized with gamma-adaptin, a trans Golgi network marker, in perinuclear sites, but did not reach plasma membranes. In order to investigate how infection altered gE localization, we made a recombinant virus, vOka-MSPgE, with ORF68 from the VZV MSP strain. VZV MSP encodes a mutant gE protein (D150N) that lacks the mAb epitope, 3B3 (Santos et al., Virology 275, 306-317, 2000), whereas Met-gE protein binds mAb 3B3. Within 48 h after Met-gE cells were infected with vOka-MSPgE, the steady-state distribution of Met-gE protein extended beyond the perinuclear areas to other cytoplasmic sites and to plasma membranes. A second recombinant, vOka-MSPgE without gI (vOka-MSPgEdeltagI), was constructed to investigate Met-gE protein distribution in the absence of gI. The redistribution of Met-gE protein which was observed by 48 h after vOka-MSPgE infection did not occur until 5 days (140 h) within vOka-MSPgEdeltagI infected cells. After vOka-MSPgE infection of Met-gE cells, most Met-gE protein was in the final 94K mature form by 72 h. However, progression to predominance of mature gE was delayed in Met-gE cells infected with vOka-MSPgEdeltagI. These observations confirm our hypothesis that VZV gE is essential, based upon the demonstration of restored infectivity after replacing ORF68 in a nonnative site in the genome, and provide further evidence of the role of gI in facilitating the maturation and intracellular distribution of this critical VZV glycoprotein.

Doxycycline↗

PubMed1992

Changes in serum glycoprotein glycosylation during experimental inflammation in mice are general, unrelated to protein type, and opposite changes in man and rat: studies on mouse serum alpha 1-acid glycoprotein, alpha 1-esterase, and alpha 1-protease inhibitor.

Using the method of crossed affinity immunoelectrophoresis with concanavalin A in combination with digital image processing, unrelated serum glycoproteins from normal mice and from mice undergoing an experimentally induced inflammation were analyzed for their carbohydrate-derived microheterogeneity profile. This profile changed in a generalized way in mouse serum samples taken at various time intervals after the initial induction of inflammation. The changes are not related to the acute-phase behavior of the protein itself (be it positive, negative, or nonreacting), and they are opposite to the changes in microheterogeneity profiles reported previously for glycoproteins during the acute phase in human and rat sera. These findings are discussed in the context of the biosynthetic control of glycoprotein glycosylation during the acute-phase response.

Acute-Phase Reaction↗

PubMed1977

Serum glycoproteins in the liver diseases. IV. Alpha-1 acid glycoprotein level in liver cirrhosis.

Circulating alpha-1 acid glycoprotein level in cirrhotic patients was determined by radioimmunoassay, and was compared to the ones in normal subjects and chronic active hepatitis with sublobular necrosis. Serum alpha-1 acid glycoprotein levels in liver cirrhosis (p less than 0.001) and chronic active hepatitis with sublobular necrosis (p less than 0.02) were significantly reduced comparing to the normal subjects, although any statistically significant difference was not observed between the formers. In liver cirrhosis, thie serum alpha-1 acid glycoprotein level correlated negatively with serum albumin concentration but neither with serum alpha-1 globulin fraction nor with Indocyanine green clearance rate.

Chronic Disease↗

PubMed2000

The extracellular part of glycoprotein E of bovine herpesvirus 1 is sufficient for complex formation with glycoprotein I but not for cell-to-cell spread.

Glycoproteins gE and gI of bovine herpesvirus 1 (BHV-1) are type I transmembrane proteins that can form a complex that is involved in cell-to-cell spread mechanisms. The extracellular domains of both proteins have cysteine-rich regions that are also found in the homologous proteins of other alpha-herpesviruses. The extracellular domain of gE has two conserved cysteine-rich regions: C1 and C2. The other conserved regions in gE are located between C2 and transmembrane region and in the cytoplasmic domain of gE. We studied the complex formation between gE and gI using a series of truncated gE proteins and a full length form and a secreted form of gI. All proteins were expressed in recombinant baculoviruses. To analyse the complex formation between these polypeptides we used monoclonal antibodies (MAbs 67 and 75) that specifically react with the gE/gI complex and not with separately expressed glycoproteins gE and gI alone. This analysis showed that the BHV-1 gE/gI complex can be formed in insect cells after a co-infection with baculoviruses expressing gE and gI in their full length form. When secreted forms of gE and gI were expressed after co-infection, the gE/gI complex was still formed and could also be detected in the tissue culture medium. This gE/gI complex was also formed after mixing the tissue culture media of insect cells expressing the secreted form or gE or gI separately. The smallest part of gE that still formed a complex is encoded by the first 246 residues of gE. This extracellular domain contains only the C1 region, showing that the C2 region is not essential for gE/gI complex formation. Shorter forms of gE encoding the C1 region did not form a detectable complex. We also found that the formation of gE/gI complex is not sufficient for normal cell-to-cell spread of BHV-1. A recombinant BHV-1 gE TM-virus, expressing a truncated glycoprotein E from which the transmembrane and cytoplasmic domain were removed, forms plaques as small as a gE null mutant.

Animals↗

PubMed1983

Viral membrane glycoproteins: comparison of the amino terminal amino acid sequences of the precursor and mature glycoproteins of three serotypes of vesicular stomatitis virus.

The NH2-terminal amino acid sequences of the envelope glycoproteins and the in vitro synthesized, nonglycosylated precursors of the glycoproteins of three serotypes, namely Indiana (Toronto), Cocal, and New Jersey (Concan) of vesicular stomatitis virus were determined. A comparison of the sequences showed little homology in the signal peptides present in the nonglycosylated precursors except for their high hydrophobic amino acid content. In contrast, the NH2-terminal amino acid sequences of the mature envelope glycoproteins revealed extensive homology suggesting that this region is conserved and may be involved in essential biological function(s) of the rhabdovirus.

Amino Acid Sequence↗

PubMed1988

Sequence of a bovine herpesvirus type-1 glycoprotein gene that is homologous to the herpes simplex gene for the glycoprotein gB.

The 130-kDa bovine herpesvirus-1 (BHV-1) glycoprotein GVP 6 was found to cross-react immunologically with the herpes simplex glycoprotein gB. Antibodies in polyclonal serum against gB immunoprecipitated GVP 6 and its cleavage products from a lysate of BHV-1-infected cells. Conversely, polyclonal serum against GVP 6 precipitated gB from HSV-1-infected cell lysates. Sera against the other glycoproteins did not demonstrate cross-reactivity. A 3.6-kb Kpnl-Hpal fragment of BHV-1 DNA that hybridized to the gene for gB was cloned and the nucleotide sequence of both strands was determined. The longest codon reading frame in the fragment coded for a protein that showed extensive homology with gB1 and related sequences from pseudorabies virus, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus. The strongest homologies were observed in two segments of the ectodomain, the transmembrane domain, and sequences adjacent to the transmembrane domain.

Amino Acid Sequence↗

PubMed1989

Nucleotide sequence of bovine herpesvirus type 1 glycoprotein gIII, a structural model for gIII as a new member of the immunoglobulin superfamily, and implications for the homologous glycoproteins of other herpesviruses.

The gene encoding bovine herpesvirus type 1 (BHV-1) glycoprotein gIII was mapped, cloned, and sequenced. The gene is situated between map units 0.122 and 0.135 and encodes a predicted protein of 521 amino acids. The identity of the sequenced gene has been verified previously by expression of immunologically authentic recombinant BHV-1 gIII (Fitzpatrick et al. (1988) J. Virol. 62, 4239-4248). Comparison of the BHV-1 gIII amino acid sequence with the homologous glycoproteins of other alphaherpesviruses revealed significant homology in the carboxy-terminal half of the molecules, including six invariant cysteine residues. A 96 amino acid domain with significant homology to class II major histocompatibility complex (MHC) antigen constant domains was identified in the conserved carboxy-terminal half of BHV-1 gIII. This domain is flanked by two other similarly sized domains which may be related to other immunoglobulin (Ig) superfamily domains. These homologies support a model for the structure of BHV-1 gIII as a new member of the Ig superfamily. Elements of the model may be applicable to the homologous glycoproteins of other herpesviruses and relevant to the immunobiology of herpesvirus infections.

Amino Acid Sequence↗