51
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Watanabe N, Nishi M, Ikawa Y, Amanuma H. A deletion in the Friend spleen focus-forming virus env gene is necessary for its product (gp55) to be leukemogenic. J Virol 1990; 64:2678-86. [PMID: 2159537 PMCID: PMC249446 DOI: 10.1128/jvi.64.6.2678-2686.1990] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
To determine the biological significance of the 585-base-pair deletion in the env gene of Friend spleen focus-forming virus (SFFV) encoding a leukemogenic glycoprotein (gp55), we examined the pathogenicity of a constructed mutant SFFV (SFFVDF). In the SFFVDF genome, the env deletion was filled in with the corresponding env sequence of Friend mink cell focus-forming virus, whereas the 6-base-pair duplication and the single base insertion near the 3' terminus of SFFV env remained intact. SFFVDF was nonpathogenic in adult mice. During passage of SFFVDF through newborn mice, we recovered various pathogenic variant SFFVs. Molecular analyses of variant SFFV genome DNAs revealed the presence of a distinct deletion in each env gene, which was similar but not identical to that in the wild-type SFFV env. Starting with the SFFVDF genome DNA, other mutant SFFV genome DNAs were constructed in which the sequence coding for the gp70/p15E proteolytic cleavage site present in the SFFVDF genome was modified by oligonucleotide-directed site-specific mutagenesis to prevent the cleavage. These mutant SFFVs were also nonpathogenic. These results indicate that for the pathogenic activity of gp55, a certain env deletion is necessary which causes production of a gp70-p15E fusion protein with an absence of at least the N-terminal one-third of the p15E-coding region.
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Affiliation(s)
- N Watanabe
- Laboratory of Gene Technology and Safety, Institute of Physical and Chemical Research (RIKEN), Ibaraki, Japan
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52
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Ollert MW, Calderone RA. A monoclonal antibody that defines a surface antigen on Candida albicans hyphae cross-reacts with yeast cell protoplasts. Infect Immun 1990; 58:625-31. [PMID: 1689699 PMCID: PMC258511 DOI: 10.1128/iai.58.3.625-631.1990] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Female BALB/c mice were immunized with a whole-hyphal-cell extract obtained from Candida albicans wild-type strain 4918 grown in Lee medium. Monoclonal antibody (MAb)-producing hybridomas were prepared by fusing immune splenocytes with NS-1 myeloma cells. One of the hybrid cell clones (1.183) secreted an immunoglobulin G1 antibody that reacted with C. albicans hyphae in an indirect immunofluorescence assay but not with yeast cells and pseudohyphal segments directly originating from parent blastoconidia. In the same assay eight of nine recent clinical C. albicans isolates and Candida stellatoidea tested positive for hyphal cell-specific reactivity with MAb 1.183. The recognized antigen on hyphal cells was sensitive to heat treatment, beta-mercaptoethanol reduction, and proteolysis with pronase, trypsin, and subtilisin. Western blot (immunoblot) analysis of hyphal whole-cell and dithiothreitol extracts with MAb 1.183 revealed two major proteins with approximate molecular masses of 55 and 60 kilodaltons (kDa) under reducing conditions. Endo-alpha-N-acetylgalactosaminidase (O-glycanase) treatment reduced the molecular mass of the 60-kDa protein slightly but did not affect recognition by MAb 1.183, whereas peptide:N-glycosidase F (N-glycanase) had no effect on either protein. When exponentially growing yeast cells were treated sequentially with EDTA, beta-mercaptoethanol, and Zymolase to form protoplasts, a specific immunofluorescence signal was obtained with MAb 1.183. In a Western blot, MAb 1.183 showed reactivity with a 20-kDa protein in the sodium dodecyl sulfate extract from protoplasts, whereas no reactivity was found with cell wall material obtained from yeast cells. In summary, these experiments indicated that specific cell surface components from C. albicans hyphae are related to antigens which are present in yeast cells but are not detectable on the surface of the latter.
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Affiliation(s)
- M W Ollert
- Department of Microbiology, School of Medicine, Georgetown University, Washington, D.C. 20007
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53
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Stein BS, Engleman EG. Intracellular processing of the gp160 HIV-1 envelope precursor. Endoproteolytic cleavage occurs in a cis or medial compartment of the Golgi complex. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39849-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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54
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Geyer R, Dabrowski J, Dabrowski U, Linder D, Schlüter M, Schott HH, Stirm S. Oligosaccharides at individual glycosylation sites in glycoprotein 71 of Friend murine leukemia virus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 187:95-110. [PMID: 2298213 DOI: 10.1111/j.1432-1033.1990.tb15281.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Glycoprotein 71 from Friend murine leukemia virus was digested with proteases and the glycopeptides obtained were isolated and assigned, by amino acid sequencing, to the eight N-glycosylated asparagines in the molecule; only Asn334 and Asn341 could not be separated. The oligosaccharides liberated from each glycopeptide by endo-beta-N-acetylglucosaminidase H, or by peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F, were fractionated and subjected to structural analysis by one- and two-dimensional 1H NMR, as well as by methylation/gas-liquid-chromatography/mass-fragmentography. At each glycosylation site, the substituents were found to be heterogeneous including, at Asn334/341 and Asn410, substitution by different classes of N-glycans: oligomannosidic oligosaccharides, mainly Man alpha 1----6(Man alpha 1----3)Man alpha 1----6(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4GlcNAc beta 1----, were detected at Asn168, Asn334/341 and Asn410. Hybrid species, partially sialylated, intersected and (proximally) funcosylated Man alpha 1----6(Man alpha 1----3)Man alpha 1----6 and Man alpha 1----3Man alpha 1----6 and Man alpha 1----3Man alpha 1----6(Gal beta 1----4GlcNAc beta 1----2Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4GlcNAc beta 1----, were found at Asn12, as previously published [Schlüter, M., Linder, D., Geyer, R., Hunsmann, H., Schneider, J. & Stirm, S. (1984) FEBS Lett. 169, 194-198] and at Asn334/341. N-Acetyllactosaminic glycans, mainly partially intersected and fucosylated NeuAc alpha 2----3 or Gal alpha 1----3Gal beta 1----4GlcNAc beta 1----2Man alpha 1----6(NeuAc alpha 2----6 or NeuAc alpha 2----3Gal-beta 1----4GlcNAc beta 1----2Man alpha 1----3)Man beta 1----4GlcNac beta 1----4GlcNAc beta 1---- with some bifurcation at ----6Man alpha 1----6, were obtained from Asn266, Asn302, Asn334/341, Asn374 and Asn410. In addition, Thr268, Thr277, Thr279, Thr304/309, as well as Ser273 and Ser275, were found to be O-glycosidically substituted by Gal beta 1----3GalNAc alpha 1----, monosialylated or desialylated at position 3 of Gal or/and position 6 of GalNAc.
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Affiliation(s)
- R Geyer
- Biochemisches Institut am Klinikum der Justus-Liebig-Universitat, Giessen, Federal Republic of Germany
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55
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Affiliation(s)
- E Hunter
- Department of Microbiology, University of Alabama, Birmingham 35294
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56
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Inhibition of mucin glycosylation by aryl-N-acetyl-α-galactosaminides in human colon cancer cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47297-9] [Citation(s) in RCA: 195] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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57
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Pinter A, Honnen WJ. Biochemical characterization of cell-associated and extracellular products of the Friend spleen focus-forming virus env gene. Virology 1989; 173:136-43. [PMID: 2554567 DOI: 10.1016/0042-6822(89)90229-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The mature product of the env gene of Friend spleen focus-forming viruses (F-SFFV) is efficiently released from both leukemia cells and infected fibroblasts. Analyses of the kinetics of env protein synthesis and secretion in NRK cells infected with the Lilly-Steeves strain of SFFVp indicated that this product, gp65, was formed rapidly and remained stably associated with cells for up to 4 hr, at which point it was first detected in supernatant medium. By 12 hr after synthesis, greater than 95% of gp65 was found extracellularly. The release of this component was effectively blocked by 10 mM 1-deoxynojirimycin, an inhibitor of oligosaccharide processing, demonstrating a requirement for processing of high mannose precursor oligosaccharides in the secretion of gp65. Similar oligosaccharide substituents were found on cell-associated and extracellular forms of gp65. Enzymatic deglycosylation experiments demonstrated that in addition to the predicted four N-linked oligosaccharides, gp65 contains O-linked carbohydrates which are resistant to the action of peptide N-Glycanase F, but sensitive to neuraminidase and O-Glycanase. These structures may be related to O-linked oligosaccharides previously found on the env gene products of murine leukemia viruses. Comparison of the sizes of the deglycosylated forms of cell-associated and supernatant gp65 demonstrated that the extracellular molecules are approximately 3 kDa smaller than the cell-associated components. These data suggest the involvement of proteolysis at a C-terminal site in the release of gp65 from the plasma membrane.
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Affiliation(s)
- A Pinter
- Laboratory of Retroviral Biology, Public Health Research Institute, New York, New York 10016
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58
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Thomas LJ, Humphreys RE, Knapp W, Nguyen QV. Time-dependent cleavage of a high-mannose form of Ii to p25 in an intracellular compartment. Am J Hematol 1989; 32:167-77. [PMID: 2816909 DOI: 10.1002/ajh.2830320303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The cleavage of a high-mannose form of Ii to p25 was demonstrated in an intracellular compartment of B cells. Subcellular fractions of 72 hr-activated B cells, separated by Percoll density gradient centrifugation, were immunoprecipitated with anti-class II or anti-Ii serum and characterized for 5'-nucleotidase, acid phosphatase, and radiolabeled transferrin. The cleavage of p25 from Ii as a C-terminal fragment occurred from 20 to 60 min after synthesis in an intracellular compartment which was intermediate in density between lysosomal and plasma membrane fractions and coincided with the lighter to two internalized transferrin compartments. Chloroquine or monensin treatments, at maximal nontoxic doses, which block Golgi and lysosomal functions, did not seem to alter the cleavage of Ii to p25. p25 molecules were reduced to about 10,500 daltons by treatment with endoglycosidases F or H. We conclude that p25 was generated from a high mannose form of Ii in the endoplasmic reticulum or cis-Golgi. This finding could either implicate that site for class II MHC desetope charging with foreign peptides or reflect a mechanism for degradation of "excess" Ii molecules.
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Affiliation(s)
- L J Thomas
- Department of Pediatrics, University of Massachusetts Medical School, Worcester 01655
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59
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Purcell DF, Deacon NJ, McKenzie IF. The human non-lineage antigen CD46 (HuLy-m5) and primate retroviral gp70 molecules share protein-defined antigenic determinants. Immunol Cell Biol 1989; 67 ( Pt 5):279-89. [PMID: 2482250 DOI: 10.1038/icb.1989.42] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The CD46 lymphocyte surface antigen of man (until recently called HuLy-m5), and defined by the E4.3 monoclonal antibody (MoAb), shares cross-reactive antigenic epitopes with the envelope gp70 glycoproteins of gibbon ape leukaemia virus (GaLV) and Mason Pfizer monkey virus (MPMV) primate retroviruses. It is now shown that the cross-reactive antigenic epitope shared by these three molecules is determined solely by the protein portion of these glycoproteins, and that the N-linked and O-linked carbohydrate moieties of these glycoproteins do not directly or sterically contribute to the antigenic cross-reactivity. When CD46 molecules (mol.wt = 66 and 56 kDa) from human thymocytes were stripped of sialic acid with neuraminidase, or stripped of N-linked carbohydrate with endoglycosidase F, the E4.3 MoAb was still able to bind and immunoprecipitate the protein core of CD46 (mol.wt = 56 and 44 kDa). Similarly, polyclonal antisera to GaLV and MPMV precipitated deglycosylated CD46, although at a reduced efficiency. The cross-reacting E4.3 MoAb, anti-GaLV and anti-MPMV antisera also immunoprecipitated HuLy-m5 primary translation protein lacking N- or O-linked carbohydrate from the in vitro translation products of human thymocyte mRNA. Thus, the antigenic cross-reactivity of CD46 molecules with GaLV gp70 and MPMV gp70 is both specific and due to protein structure rather than to carbohydrate; the findings suggest that retroviruses may have acquired a functional epitope from human CD46 or that an endogenous retroviral sequence of human may partially or completely encode the CD46 antigen.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antigens, CD/immunology
- Antigens, Differentiation/immunology
- Antigens, Viral/immunology
- Chromatography, Ion Exchange
- Cross Reactions
- Electrophoresis, Gel, Two-Dimensional
- Electrophoresis, Polyacrylamide Gel
- Epitopes/immunology
- Glycoside Hydrolases
- Humans
- Lectins
- Membrane Cofactor Protein
- Membrane Glycoproteins
- Mice
- Neuraminidase
- Plant Lectins
- Poly A/metabolism
- Precipitin Tests
- Protein Biosynthesis
- RNA, Messenger/metabolism
- Retroviridae Proteins, Oncogenic/immunology
- Simian Immunodeficiency Virus/immunology
- Thymus Gland/cytology
- Viral Envelope Proteins/immunology
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Affiliation(s)
- D F Purcell
- Department of Pathology, University of Melbourne, Parkville, Vic., Australia
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60
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Gliniak BC, Kabat D. Leukemogenic membrane glycoprotein encoded by Friend spleen focus-forming virus: transport to cell surfaces and shedding are controlled by disulfide-bonded dimerization and by cleavage of a hydrophobic membrane anchor. J Virol 1989; 63:3561-8. [PMID: 2547985 PMCID: PMC250945 DOI: 10.1128/jvi.63.9.3561-3568.1989] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The leukemogenic glycoprotein (gp55) encoded by Friend spleen focus-forming virus is predominantly retained in the rough endoplasmic reticulum (RER). However, a small proportion (ca. 5%) is processed to form a derivative that occurs on plasma membranes and causes mitosis of infected erythroblasts. We have now found that gp55 folds heterogeneously in the RER to form components with different disulfide bonds and that this difference may determine their processing fates. RER gp55 consists predominantly of monomers with intrachain disulfide bonds. In contrast, the processed molecules are disulfide-bonded dimers. These dimers are extensively modified in transit to cell surfaces by conversion of four N-linked high-mannose oligosaccharides to complex derivatives and by attachment of a sialylated O-linked oligosaccharide. The plasma membrane dimers are then slowly shed into the medium by a mechanism that involves proteolytic cleavage of approximately 25 membrane-anchoring hydrophobic amino acids from the carboxyl termini of the glycoproteins. Consequently, shed molecules have shorter polypeptide chains than cell-associated gp55. We conclude that gp55 folds into different disulfide-bonded components that do not substantially isomerize, and that only one specific dimer is competent for export from the RER. Mitogenic activity of gp55 could be caused by the cell surface dimers, by the shed derivative, or by the carboxyl-terminal hydrophobic anchors that remain in the membranes after the shedding reaction.
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Affiliation(s)
- B C Gliniak
- Department of Biochemistry, School of Medicine, Oregon Health Sciences University, Portland 97201-3098
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61
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Nilsson T, Jackson M, Peterson PA. Short cytoplasmic sequences serve as retention signals for transmembrane proteins in the endoplasmic reticulum. Cell 1989; 58:707-18. [PMID: 2527615 DOI: 10.1016/0092-8674(89)90105-0] [Citation(s) in RCA: 400] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The adenoviral transmembrane E3/19K glycoprotein is a resident of the endoplasmic reticulum. Here we show that the last six amino acid residues of the 15-membered cytoplasmic tail are necessary and sufficient for the ER retention. These residues can be transplanted onto the cytoplasmic tail of other membrane-bound proteins such that ER residency is conferred. Deletion analysis demonstrated that no single amino acid residue is responsible for the retention. The identified structural motif must occupy the extreme COOH-terminal position to be functional. An endogenous transmembrane ER protein, UDP-glucuronosyltransferase, also contains a retention signal in its cytoplasmic tail. We suggest that short linear sequences occupying the extreme COOH-terminal position of transmembrane ER proteins serve as retention signals.
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Affiliation(s)
- T Nilsson
- Department of Immunology, Research Institute of Scripps Clinic, La Jolla, California 92037
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62
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Pinter A, Honnen WJ, Tilley SA, Bona C, Zaghouani H, Gorny MK, Zolla-Pazner S. Oligomeric structure of gp41, the transmembrane protein of human immunodeficiency virus type 1. J Virol 1989; 63:2674-9. [PMID: 2786089 PMCID: PMC250755 DOI: 10.1128/jvi.63.6.2674-2679.1989] [Citation(s) in RCA: 239] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We characterized the structural forms of the human immunodeficiency virus env-encoded proteins with a panel of monoclonal and polyclonal antibodies. Western blot (immunoblot) assays with antibodies specific for gp41 invariably recognized a major component of 160 kilodaltons and a less intense component of 120 kilodaltons in viral lysates. We demonstrated that these species are noncovalently associated tetramers and trimers of gp41 which represent the native form of this protein in virions. These complexes were stable when boiled in the presence of low concentrations of sodium dodecyl sulfate but were dissociated to gp41 monomers at high sodium dodecyl sulfate concentrations. Moreover, two human monoclonal antibodies preferentially recognized the oligomeric complexes over monomeric gp41 in Western blots, indicating the presence of epitopes recognized by the human immune system on the gp41 multimers which are not efficiently expressed by the dissociated monomers. The demonstration of the existence of multimeric env complexes and the enhanced and altered antigenicity of such multimers may be relevant to the design of subunit and recombinant human immunodeficiency virus env vaccines.
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Affiliation(s)
- A Pinter
- Public Health Research Institute of the City of New York, New York 10016
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63
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Britt WJ, Vugler LG. Processing of the gp55-116 envelope glycoprotein complex (gB) of human cytomegalovirus. J Virol 1989; 63:403-10. [PMID: 2535741 PMCID: PMC247697 DOI: 10.1128/jvi.63.1.403-410.1989] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The processing pathway of the major envelope glycoprotein complex, gp55-116 (gB), of human cytomegalovirus was studied using inhibitors of glycosylation and endoglycosidases. The results of these studies indicated that the mature gp55-116 is synthesized by the addition of both simple and complex N-linked sugars to a nonglycosylated precursor of estimated Mr 105,000. In a rapid processing step, the Mr 105,000 precursor is glycosylated to a protein of Mr 150,000 (gp150) which contains only endoglycosidase H-sensitive sugar linkages. The gp150 is then processed relatively slowly to a Mr 165,000 to 170,000 species (gp165-170), which is then cleaved to yield the mature gp55-116. Monensin prevented the final processing steps of the gp150, including cleavage, suggesting that transport through the Golgi apparatus is required for complete processing. Digestion of the intracellular forms of this complex as well as the virion forms confirmed the above findings and indicated that the mature virion form of gp55 contains 8,000 daltons of N-linked sugars. The virion gp116 contains some 52,000 to 57,000 daltons of N-linked carbohydrates and approximately 5,000 daltons of O-linked sugars.
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Affiliation(s)
- W J Britt
- Department of Pediatrics and Microbiology, University of Alabama, Birmingham 35294
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64
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Tsai WP, Oroszlan S. Novel glycosylation pathways of retroviral envelope proteins identified with avian reticuloendotheliosis virus. J Virol 1988; 62:3167-74. [PMID: 2841469 PMCID: PMC253434 DOI: 10.1128/jvi.62.9.3167-3174.1988] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Previously, we identified two mature glycoproteins, gp90, the surface glycoprotein, and gp20, the transmembrane protein, from avian reticuloendotheliosis virus and an avian reticuloendotheliosis virus env gene-encoded intracellular polyprotein gPr77env, but the precise relationship of gPr77env to the mature envelope proteins was not determined (W.-P. Tsai, T.D. Copeland, and S. Oroszlan, Virology 155:567-583, 1986). In the present study, using metabolic labeling of viral proteins with [35S]cysteine, radioimmunoprecipitation, and carbohydrate structure analysis, we have identified a higher-molecular-weight endo-H-resistant env gene-encoded polyprotein designated gPr115env in addition to the endo-H-sensitive gPr77env. It appears that gPr77env is the primary polyprotein precursor, modified with mannosyloligosaccharides that are processed into sialic-acid-rich extraordinarily large complex-type carbohydrates (up to 17 kilodaltons for each N-linked site) on the gp90 domain but not on the gPr22 domain. In this process, gPr77env is converted into the apparently endo-H-resistant secondary polyprotein, gPr115env, which is rapidly processed into gp90 and gPr22. The proteolytic processing which occurs only after the appearance of an endo-H resistant precursor is now clearly demonstrated for a retrovirus. Some important aspects of carbohydrate structure, including the site-specific glycosylation, as well as the intracellular location and nature of the potential enzyme involved in the proteolytic cleavage of gPr115env are discussed.
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Affiliation(s)
- W P Tsai
- Laboratory of Molecular Virology and Carcinogenesis, NCI-Frederick Cancer Research Facility, Maryland 21701
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