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At least 163 records · Page 9Linked to original sources
PubMed1997

High degree of sensitivity of the simian immunodeficiency virus (SIVmac) envelope glycoprotein subunit association to amino acid changes in the glycoprotein 41 ectodomain.

The infection of macaques by simian immunodeficiency virus (SIVmac) represents an attractive model to study the pathogenic determinants of primate and human immunodeficiency viruses. The utility of this model would be enhanced if genetic changes in human immunodeficiency virus (HIV-1) associated with interesting in vitro properties would, when introduced into SIVmac, result in similar phenotypes. In this study, we introduced amino acid changes into the SIVmac239 envelope glycoproteins that, in the context of the HIV-1 envelope glycoproteins, disproportionately attenuated in vitro cytopathic effects compared with the viral replication rate. Amino acid changes in the SIVmac239 gp41 ectodomain altered the noncovalent association of the gp120 and gp41 glycoproteins significantly more than did analogous changes in the HIV-1 envelope glycoproteins. Decreases in the affinity of the gp120-gp41 interaction were observed and were associated with a dramatic attenuation of virus replication not seen in the HIV-1 studies. The increased sensitivity of the SIVmac gp120-gp41 interaction to amino acid changes presents an obstacle to the direct extension of results obtained with the HIV-1 envelope glycoproteins to the SIVmacaque model.

Amino Acid Sequence↗
PubMed1987

Herpes simplex virus type 2 glycoprotein biogenesis: effect of monensin on glycoprotein maturation, intracellular transport and virus infectivity.

The ionophore monensin inhibited the formation of herpes simplex virus type 2 (HSV-2) particles by about 30% but the yields of infectious particles were reduced to 5% and 1% for cell-associated and extracellular virus, respectively. The presence of monensin did not affect the processing of the two viral glycoproteins gB-2 and gG-2. However, two other glycoproteins, gC-2 and gD-2, were not processed to their fully mature forms in the monensin-treated cells and only the faster moving pgC-2 and pgD-2 were detected. The cell-associated virus particles contained the glycoproteins gB-2, gC-2, gD-2 and gG-2, whereas the extracellular virus particles contained only gG-2 glycoprotein. These results suggest that HSV-2 particles containing all the viral glycoproteins are transported via the Golgi apparatus to the cell surface but that virus particles containing only gG-2 may follow a different pathway for transport and release.

Animals↗
PubMed1989

Temperature-sensitive mutants of bovine herpesvirus type 1: mutants which make unaltered levels of 'early' glycoproteins but fail to synthesize a 'late' glycoprotein.

The major glycoproteins of bovine herpesvirus type 1 showed distinct temporal patterns of expression. The glycoproteins GVP 11 and GVP 6 as well as its cleavage products, GVP 11a and GVP 16, were expressed early in the infectious process, whereas GVP 9 was expressed late. Temperature-sensitive mutants were developed and characterized. Mutants belonging to two complementation groups were unable to synthesize DNA at 40 degrees C, the non-permissive temperature. In cells infected with these mutants the late glycoprotein GVP 9 was not synthesized at 40 degrees C, whereas the synthesis of the early glycoproteins GVP 11 and GVP 6 continued at wild-type levels. These studies suggest that the transition from early to late glycoprotein synthesis is linked to viral DNA synthesis.

Animals↗
PubMed1986

Myelin-associated glycoprotein shares an antigenic determinant with a glycoprotein of human melanoma cells.

A sulfated 100K-dalton glycoprotein has been shown to be released into the culture medium of melanoma cells. Monoclonal antibodies 10C5 and 11B5, which were raised to human melanoma cells, as well as HNK-1 bind to this glycoprotein. It is shown here that mouse anti-myelin-associated glycoprotein (MAG) carbohydrate antibodies raised to human MAG and a human IgM paraprotein associated with neuropathy also bind to the same 100K molecule. However, anti-MAG antibodies recognizing peptide epitopes do not appear to react with this glycoprotein of melanoma cells, a result suggesting that its similarity to MAG is restricted to shared carbohydrate moieties. The anti-melanoma antibodies (10C5 and 11B5) resemble HNK-1 in binding to MAG and to some 19-28K-dalton glycoproteins and sulfated, glucuronic acid-containing sphingoglycolipids of the peripheral nervous system (PNS). In addition, the anti-melanoma antibodies cross-react with neural cell adhesion molecule (N-CAM), an observation emphasizing the shared antigenicity between MAG and other adhesion molecules. The results demonstrate that the anti-melanoma antibodies fall into a class of monoclonal antibodies (including HNK-1, human IgM paraproteins associated with neuropathy, anti-human MAG antibodies, and L2 antibodies) that are characterized by reactivity against related carbohydrate determinants shared by human MAG, N-CAM, and several protein and lipid glycoconjugates of the PNS.

Antibodies, Neoplasm↗
PubMed1995

Gonadal function and glycoprotein hormones in the carbohydrate-deficient glycoprotein (CDG) syndrome.

Six females and six males with carbohydrate-deficient glycoprotein (CDG) syndrome type I, aged 4 months to 43 years, were examined for gonadal function and electrophoretic isoform patterns of four glycoprotein hormones: FSH, LH, TSH and erythropoietin. The female patients had a hypergonadotrophic hypogonadism from an early age without detectable ovaries in three cases. In the males, testosterone levels tended to be low with normal or slightly raised gonadotrophin values. None of the four glycoprotein hormone showed any signs of carbohydrate deficiency of the same type as in many liver-synthesized circulating glycoproteins. It is concluded that females with CDG syndrome type I have primary ovarian failure, and that the syndrome does not affect the terminal charged carbohydrate portion in gonadotrophins, TSH or erythropoietin. The characteristic carbohydrate deficiency in some circulating glycoproteins is thus not a generalized feature in this disease.

Adolescent↗
PubMed1982

Revertant analysis of a temperature-sensitive mutant of Newcastle disease virus with defective glycoproteins: implication of the fusion glycoprotein in cell killing and isolation of a neuraminidase-deficient hemagglutinating virus.

Biological and molecular properties of a temperature-sensitive mutant (C1) of Newcastle disease virus and its revertants were analyzed. C1 exhibited three temperature-sensitive alterations (plaque formation, virion assembly, and cytopathogenicity) and several defects which were also present at the permissive temperature. C1 virions contained low amounts of hemagglutinin-neuraminidase glycopeptides and consequently were deficient in hemagglutinating and neuraminidase activities. These virions also contained defective fusion glycoproteins which rendered them poorly hemolytic and slow to penetrate cultured chicken embryo cells. The biological activities of the membrane glycoproteins were recovered sequentially in a series of plaque-forming revertants. The coreversion of hemolysis, membrane-penetrating activities, and cytopathogenicity in the first-step revertant (S1) suggested that fusion glycoproteins were major contributors to cellular destruction. This revertant also provided evidence of a role for fusion glycoproteins in virion assembly. From S1 we isolated a large-plaque-forming revertant (L1) that assembled wild-type amounts of biologically active hemagglutinin-neuraminidase glycoproteins into virions. Although it was normal for hemagglutination, L1 had less than 3% of the neuraminidase activity of the wild type, demonstrating that these two activities can be uncoupled genetically. The neuraminidase deficiency of L1 did not impair its virulence in ovo or its reproduction in cultured cells.

Animals↗
PubMed1985

Demonstration of three major species of pseudorabies virus glycoproteins and identification of a disulfide-linked glycoprotein complex.

The glycoproteins of pseudorabies virus (PRV) Phylaxia were characterized with monoclonal antibodies as specific reagents. Three major structural glycoproteins with molecular weights of 155,000 (155K) (gC), 122K (gA), and 90K (gB) could be identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. We investigated the processing of glycoproteins gA, gB, and gC by in vitro translation, pulse-chase experiments, and in the presence of the ionophore monensin which inhibits glycosylation. gA and gB were found to compose a single polypeptide, whereas gC was found to be a disulfide-linked glycoprotein complex. Immunoprecipitates formed with the aid of anti-gC monoclonal antibodies gave rise to three glycoprotein bands (gC0 [120K], gC1 [67K], and gC2 [58K]) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Limited proteolysis of gC0, gC1, and gC2 resulted in peptide maps of gC0 related to those of both gC1 and gC2. No common peptide bands between gC1 and gC2, however, were seen. We suggest that (i) gC1 and gC2 arise by proteolytic cleavage from the same precursor molecule and stay joined via disulfide bridges and (ii) gC0 is an uncleaved precursor.

Animals↗
PubMed1985

Cross-reactivity between herpes simplex virus glycoprotein B and a 63,000-dalton varicella-zoster virus envelope glycoprotein.

Cross-reactive monoclonal antibodies recognizing both herpes simplex virus (HSV) glycoprotein B and a major 63,000-dalton varicella-zoster virus (VZV) envelope glycoprotein were isolated and found to neutralize VZV infection in vitro. None of the other VZV glycoproteins was recognized by any polyclonal anti-HSV serum tested. These results demonstrate that HSV glycoprotein B and the 63,000-dalton VZV glycoprotein share antigenic epitopes and raise the possibility that these two proteins have a similar function in infection.

Antibodies, Monoclonal↗
PubMed1987

Antigenic relatedness between glycoproteins of human respiratory syncytial virus subgroups A and B: evaluation of the contributions of F and G glycoproteins to immunity.

The degree of antigenic relatedness between human respiratory syncytial virus (RSV) subgroups A and B was estimated from antibody responses induced in cotton rats by respiratory tract infection with RSV. Glycoprotein-specific enzyme-linked immunosorbent assays of antibody responses induced by RSV infection demonstrated that the F glycoproteins of subgroups A and B were antigenically closely related (relatedness, R approximately 50%), whereas the G glycoproteins were only distantly related (R approximately 5%). Intermediate levels of antigenic relatedness (R approximately 25%) were seen in neutralizing antibodies from cotton rats infected with RSV of the two subgroups. Immunity against the F glycoprotein of subgroup A, induced by vaccinia-A2-F, conferred a high level of protection which was of comparable magnitude against challenge by RSV of either subgroup. In comparison, immunity against the G glycoprotein of subgroup A, induced by vaccinia-A2-G, conferred less complete, but significant, protection. Importantly, in vaccinia-A2-G-immunized animals, suppression of homologous challenge virus replication was significantly greater (13-fold) than that observed for the heterologous virus.

Animals↗
PubMed2000

Pseudotyping of glycoprotein D-deficient herpes simplex virus type 1 with vesicular stomatitis virus glycoprotein G enables mutant virus attachment and entry.

The use of herpes simplex virus (HSV) vectors for in vivo gene therapy will require the targeting of vector infection to specific cell types in certain in vivo applications. Because HSV glycoprotein D (gD) imparts a broad host range for viral infection through recognition of ubiquitous host cell receptors, vector targeting will require the manipulation of gD to provide new cell recognition specificities in a manner designed to preserve gD's essential role in virus entry. In this study, we have determined whether an entry-incompetent HSV mutant with deletions of all Us glycoproteins, including gD, can be complemented by a foreign attachment/entry protein with a different receptor-binding specificity, the vesicular stomatitis virus glycoprotein G (VSV-G). The results showed that transiently expressed VSV-G was incorporated into gD-deficient HSV envelopes and that the resulting pseudotyped virus formed plaques on gD-expressing VD60 cells, albeit at a 50-fold-reduced level compared to that of wild-type gD. This reduction may be related to differences in the entry pathways used by VSV and HSV or to the observed lower rate of incorporation of VSV-G into virus envelopes than that of gD. The rate of VSV-G incorporation was greatly improved by using recombinant molecules in which the transmembrane domain of HSV glycoprotein B or D was substituted for that of VSV-G, but these recombinant molecules failed to promote virus entry. These results show that foreign glycoproteins can be incorporated into the HSV envelope during replication and that gD can be dispensed with on the condition that a suitable attachment/entry function is provided.

Gene Targeting↗
PubMed2001

Glycoproteins secreted from suspension-cultured tobacco BY2 cells have distinct glycan structures from intracellular glycoproteins.

Glycan structures of glycoproteins secreted in the spent medium of tobacco BY2 suspension-cultured cells were analyzed. The N-glycans were liberated by hydrazinolysis and the resulting oligosaccharides were labeled with 2-aminopyridine. The pyridylaminated (PA) glycans were purified by reversed-phase and size-fractionation HPLC. The structures of the PA sugar chains were identified by a combination of the two-dimensional PA sugar chain mapping, MS analysis, and exoglycosidase digestion. The ratio (40:60) of the amount of glycans with high-mannose-type structure to that with plant-complex-type structure of extracellular glycoproteins is significantly different from that (ratio 10:90) previously found in intracellular glycoproteins [Palacpac et al., Biosci. Biotechnol. Biochem. 63 (1999) 35-39]. Extracellular glycoproteins have six distinct N-glycans (marked by *) from intracellular glycoproteins, and the high-mannose-type structures account for nearly 40% (Man5GlcNAc2, 28.8%; Man6GlcNAc2*, 6.4%; and Man7GlcNAc2*, 3.8%), while the plant-complex-type structures account for nearly 60% (GlcNAc2Man3Xyl1GlcNAc2*, 32.1%; GlcNAc1Man3Xyl1GlcNAc2 (containing two isomers)*, 6.2%; GlcNAc2Man3GlcNAc2*, 4.9%; Man3Xyl1Fuc1GlcNAc2, 8.3%; and Man3Xyl1GlcNAc2, 3.7%).

Carbohydrate Sequence↗
PubMed2003

First evidence for occurrence of Galbeta1-3GlcNAcbeta1-4Man unit in N-glycans of insect glycoprotein: beta1-3Gal and beta1-4GlcNAc transferases are involved in N-glycan processing of royal jelly glycoproteins.

On a way of structural analysis of total N-glycans linked to glycoproteins in royal jelly (Kimura, Y. et al., Biosci. Biotechnol. Biochem., 64, 2109-2120 (2000), Kimura, M. et al., Biosci. Biotechnol. Biochem., 66, 1985-1989 (2002)), we found that some complex type N-glycans containing a beta1-3galactose residue occur on the insect glycoproteins. Up to date, it has been considered that naturally occurring insect glycoproteins do not bear the galactose-containing N-glycans, therefore, in this report we describe the structural analysis of the complex type N-glycans of royal jelly glycoproteins. By a combination of endo- and exo-glycosidase digestions, IS-MS analysis, and 1H-NMR spectroscopy, the structures of the beta1-3 galactose-containing N-glycan were identified as the following; GlcNAcbeta1-2Manalpha1-6[GlcNAcbeta1-2(Galbeta1-3GlcNAcbeta1-4)Manalpha1-3]Manbeta1-4GlcNAcbeta1-4GlcNAc, Manalpha1-3Manalpha1-6[GlcNAcbeta1-2(Galbeta1-3GlcNAcbeta1-4)Manalpha1-3]Manbeta1-4GlcNAcbeta1-4GlcNAc, and Manalpha1-6(Manalpha1-3)Manalpha1-6[GlcNAcbeta1-2(Galbeta1-3GlcNAcbeta1-4)Manalpha1-3]Manbeta1-4GlcNAcbeta1-4GlcNAc. To our knowledge, this is the first report showing that the Galbeta1-3GlcNAcbeta1-4Man unit occurs in N-glycans of insect glycoproteins, indicating a beta1-3 galactosyl transferase and beta1-4GlcNAc transferase (GNT-IV) are expressed in the honeybee cells.

Animals↗
PubMed1976

Serum glycoproteins in the liver diseases. II. Radioimmunoassay of alpha-1 acid glycoprotein.

A radioimmunoassay for human alpha1-acid glycoprotein has been developed. 97.8% of 125I-alpha1-acid glycoprotein prepared for the assay were immunoprecipitable with specific anti-sera against the protein. alpha1-acid glycoprotein concentration in sera from normal adults was found to range between 70 and 114 mg/100 ml, with a mean of 93. Fulminant hepatitis, liver cirrhosis or chronic active hepatitis with sublobular necrosis caused a significant lowering of alpha1-acid glycoprotein concentration. Sera obtained from patients with acute hepatitis in convalescence, chronic inactive hepatitis or primary biliary cirrhosis gave normal concentration of the glycoprotein.

Adult↗
PubMed1991

Expression of human P-glycoprotein in yeast cells--effects of membrane component sterols on the activity of P-glycoprotein.

A human MDR1 cDNA was introduced into yeast cells. Immunoblot analysis and indirect immunostaining showed that some of the P-glycoprotein produced was situated in its native orientation in the yeast plasma membrane. Drug-binding activities of the recombinant P-glycoproteins were markedly decreased compared to that of the authentic P-glycoprotein. To identify the bases of decreased binding we studied the effects of membrane component sterols on the azidopine binding and found that ergosterol, which is the main sterol in the yeast membrane, and calciferol, which is produced from ergosterol by UV irradiation, inhibited azidopine binding. These sterols in yeast membrane probably inhibit the function of human P-glycoprotein as a multidrug transporter in yeast cells, because expression of P-glycoprotein in yeast cells did not confer resistance to doxorubicin.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Distribution of multi-drug resistance-associated P-glycoprotein in normal and neoplastic human tissues. Analysis with 3 monoclonal antibodies recognizing different epitopes of the P-glycoprotein molecule.

P-glycoprotein is a molecule strongly associated with multi-drug resistance to certain cytostatic drugs, including adriamycin, vincristine, and daunorubicin. Using 3 monoclonal antibodies directed at different epitopes of this molecule (JSB-1, MRK16, C219) we investigated the tissue distribution of P-glycoprotein in normal and malignant human tissues, employing a routine immunoperoxidase technique. P-glycoprotein was found in the gastrointestinal epithelium, epithelia of the bronchi, mammary gland, pancreatic ducts, renal tubules, prostate gland, salivary gland, sweat glands of the skin, as well as in bile canaliculi and ductules, the adrenal and in endothelium of capillaries in various organs, most notably the brain. Mostly the pattern of reactivity of the 3 antibodies was similar, but some distinctly different staining reactions were seen. Reactivity was found in a variety of human tumors, arising from tissues normally expressing P-glycoprotein. Knowledge of the distribution and function of this molecule in both normal and malignant tissues may predict resistance and thus may influence choice of therapy. The role of P-glycoprotein in normal tissues and its implications for chemotherapy is discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

The primary structure of a procaryotic glycoprotein. Cloning and sequencing of the cell surface glycoprotein gene of halobacteria.

The hexagonally patterned surface layer of halobacteria consists of a true glycoprotein. This procaryotic glycoprotein has recently been shown to exhibit novel features with respect to saccharide structure and saccharide biosynthesis. The primary structure and the location of glycosylation sites were determined by cloning and sequencing of the glycoprotein gene of Halobacterium halobium. According to the predicted amino acid sequence, the glycoprotein is synthesized with a N-terminal leader sequence of 34 amino acid residues reminiscent of eucaryotic and procaryotic signal peptides. A hydrophobic stretch of 21 amino acid residues at the C terminus probably serves as a transmembrane domain. 14 threonine residues are clustered adjacent to this membrane anchor and linked to these threonines are all the disaccharides of the cell surface glycoprotein. 12 N-glycosylation sites are distributed over the polypeptide chain.

Amino Acid Sequence↗
PubMed1984

[Immunochemical study of the degradation of circulating glycoproteins and the neurospecific membrane glycoprotein D2 by cathepsin D of the human brain].

Cathepsin D was isolated from human brain. A consecutive use of affinity chromatography on hemoglobin-sepharose 4B and column chromatography on hydroxylapatite resulted in a homogeneous enzyme (as was demonstrated by SDS polyacrylamide gel electrophoresis) with a molecular weight of about 48,000, 2800-fold purification and 3.4% yield. Incubation of serum proteins in the presence of purified cathepsin D resulted in a gradual decrease of immunoreactive forms of albumin, orosomucoid, transferrin, and other alpha 1, alpha 2 and beta-globulins. The degradation was revealed by crossed immunoelectrophoresis. Crossed affinity immunoelectrophoresis in the presence of ConA showed specific degradation of serum glycoproteins. Rocket immunoelectrophoresis with monospecific antisera raised against human adult brain glycoprotein D2 revealed a rapid and linear degradation of detergent-solubilized and partially purified human membrane glycoprotein D2 by purified cathepsin D. Incubation of glycoprotein D2 in the presence of cathepsin D (30 min, 37 degrees C) resulted in degradation of 95% of specific protein. An exposure of human brain membrane fragments to cathepsin D resulted in linear degradation of membrane-bound glycoprotein followed by an appearance of a soluble immunoreactive form of protein D2.

Blood Proteins↗
PubMed1993

Characterization of glycoprotein II from bovine adrenal medullary chromaffin granules. Identification of components representing the secretory vesicle counterparts of the lysosomal-associated membrane glycoproteins (lamp-1 and lamp-2).

Glycoprotein II (GpII) is a heterogenous glycoprotein isolated from the membranes of bovine chromaffin granules in the adrenal medulla. When viewed by two-dimensional electrophoresis this glycoprotein consists of two components, upper (GpIIa) and lower (GpIIb), with a molecular mass of 80,000-100,000 daltons and a pI of 4.2-4.7. NH2-terminal sequence analysis of GpIIa and GpIIb revealed sequence similarity with lysosomal membrane glycoproteins (lamp-1 and lamp-2), which was supported by sequence data of peptides from trypsin and cyanogen bromide digestions. An oligonucleotide probe was used to isolate a cDNA clone encoding the nucleotide sequence of GpIIa. The predicted amino acid sequence of GpIIa shares a 72% identity with the human lamp-1 type protein, which belongs to a highly conserved group of lysosomal-associated membrane glycoproteins (lamp proteins), whose function is still unknown. The COOH-terminal region of GpIIa was identical to the COOH-terminal region of lamp proteins. This COOH-terminal determinant has been demonstrated to be essential for the intracellular targeting of lamp proteins to lysosomes. A synthetic peptide antisera to the COOH-terminal region of GpIIa was used to show that this region is present on purified chromaffin granules and not proteolytically processed. The sequence analysis of GpIIa and immunological data confirm GpII as the secretory granule counterpart of lamp proteins and raise some questions regarding intracellular targeting between lysosomes and secretory granules within the chromaffin cell.

Adrenal Medulla↗