Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.52 (PNGase F)
1,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We isolated four monoclonal antibodies (MAbs), M38, M101, M104, and C33, which were capable of inhibiting syncytium formation induced in a human T-cell line, MOLT-4-#8, by coculture with human T-cell leukemia virus type 1 (HTLV-1)-positive human T-cell lines. The MAbs had, however, no inhibitory activity on syncytium formation induced in a human osteosarcoma line, HOS, by HTLV-1-positive T-cell lines. They also did not inhibit syncytium formation induced in MOLT-4-#8 by human immunodeficiency virus type 1-positive MOLT-4. All MAbs reacted with various human cell lines of lymphoid and nonlymphoid origins, including HTLV-1-positive T-cell lines. Furthermore, they all reacted with a murine A9 clone containing human chromosome 11 fragment q23-pter. Two MAbs, M104 and C33, immunoprecipitated a membrane antigen with the same molecular size. The antigen (henceforth called C33 antigen) was about 40 to 55 kDa in HTLV-1-negative Jurkat, CEM, MOLT-4, and normal peripheral blood CD4-positive human T cells and about 40 to 75 kDa in HTLV-1-positive C91/PL, TCL-Kan, MT-2, and in fresh HTLV-1-transformed CD4-positive human T-cell lines. Pulse-chase experiments revealed that C33 antigen was synthesized as a 35-kDa precursor that was then processed to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL. In the presence of tunicamycin, a 28-kDa protein was synthesized. The conversion from 35 kDa to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL was inhibited by monensin. Treatment with N-glycanase alone, but not with sialidase and O-glycanase in combination, completely removed the sugar moiety of C33 antigen from both HTLV-1-negative Jurkat and HTLV-1-positive C91/PL. Therefore, C33 antigen has only N-linked carbohydrates, the modification of which appears to be substantially altered in the presence of the HTLV-1 genome.
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PMID:Identification of membrane antigen C33 recognized by monoclonal antibodies inhibitory to human T-cell leukemia virus type 1 (HTLV-1)-induced syncytium formation: altered glycosylation of C33 antigen in HTLV-1-positive T cells. 173 99

Fucosidosis is an inherited lysosomal storage disease due to a deficiency of alpha-L-fucosidase activity. Exponentially growing lymphoid cell cultures from a fucosidosis patient (JH) had 16-fold lower extracellular alpha-L-fucosidase protein and 72-fold lower intracellular alpha-L-fucosidase protein with negligible catalytic activity as compared with the mean of 19 control cultures. The percentage of total alpha-L-fucosidase protein released extracellularly by JH cells was 71% as compared with 35% +/- 9% for control cells. During a 1.5 h pulse with 35S-methionine, alpha-L-fucosidase was synthesized by JH cells as an intracellular doublet with Mr of 58,000 and 56,000 and by control cells as an intracellular form with Mr = 58,000. During a subsequent 21 h chase with unlabeled methionine, JH alpha-L-fucosidase was entirely secreted. In contrast, only 25%-30% of control enzyme was secreted with the remainder retained intracellularly. Thus, JH lymphoid cells synthesized a reduced amount of alpha-L-fucosidase that was catalytically inefficient and was hypersecreted. Treatment of JH alpha-L-fucosidase with N-glycanase produced polypeptide chains with Mr of 52,000 and 54,000. Previously, treatment of control alpha-L-fucosidase with N-glycancase produced a single polypeptide chain with Mr of 52,000 (Biochem Genet 1988; 26: 401-20). The doublet polypeptide chains of alpha-L-fucosidase in JH cultures may represent expression of two distinct allelic forms of mutant alpha-L-fucosidase.
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PMID:Defective expression of alpha-L-fucosidase by lymphoid cells of a fucosidosis patient. 187 10

A novel platelet glycoprotein has been purified and characterized. This glycoprotein, designated Pltgp40, is an acidic sialylated 40,000-dalton protein that bears both O-linked and N-linked oligosaccharides. Treatment of Pltgp40 with neuraminidase resulted in a 5,000-dalton reduction in its Mr and a 1.5 Unit alkaline shift in the isoelectric point, indicating the presence of a large number of sialic acid residues. A similar size reduction and change in pl were observed after treatment of Pltgp40 with O-glycanase showing that sialic acids are present on O-linked oligosaccharides. Digestion of Pltgp40 with N-glycanase reduced the Mr to approximately 20,000 daltons but did not affect the isoelectric point, suggesting that Pltgp40 contains six to seven nonsialylated N-linked carbohydrate chains. High Mr proteins were observed in affinity purified Pltgp40 and were identified as detergent-stable protein oligomers consisting of multiple 40,000-dalton monomers. Immunodepletion and direct binding studies indicated that Pltgp40 was not equivalent to Ig Fc receptor type II, another 40,000-dalton glycoprotein expressed on platelets. However, Pltgp40 copurified with Fc receptor type II when platelet extracts were loaded onto human IgG affinity columns, raising the possibility that Pltgp40 may associate with Fc receptors or Fc receptor-lg complexes. Amino acid sequence analysis of the N-terminus of Pltgp40 was performed and confirmed that Pltgp40 is a novel platelet glycoprotein. Epitopes on Pltgp40 appear to be widely expressed because monoclonal antibodies against Pltgp40 also reacted with a variety of myeloid, lymphoid, and epithelial cells. Pltgp40 was detected on activated but not resting platelets, indicating that Pltgp40 is a platelet activation marker.
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PMID:Characterization of a novel self-associating Mr 40,000 platelet glycoprotein. 174 15

We present the characterization of a new mouse cell surface protein, recognized by the 3E8-specific monoclonal antibody. The expression of this antigen is predominantly restricted to the hematopoietic and lymphoid tissues: bone marrow, spleen, lymph node, and thymus. Immunoblot analyses show that the 3E8 determinant is present on molecules with different apparent relative masses. The 3E8 antigen migrates on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a single band of Mr 115,000 for normal nonstimulated spleen cells and thymocytes and as two bands of Mr 115,000 and Mr 125,000 for bone marrow cells and mitogen-stimulated spleen cells. The multiple sizes of the 3E8 antigens (isoforms) found on various cell lines are not due to allelic polymorphism, but instead may reflect the specific cell type or reflect the cell's state of activation or maturation. Results from lectin chromatography and N-glycanase and neuraminidase studies suggest that the 3E8 antigen is a heavily sialylated O-linked glycoprotein. The unusual features of this antigen indicate that it may be the mouse homologue of the rat W3/13 antigen and the human leukosialin/sialophorin antigens.
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PMID:Identification and characterization of a mouse cell surface antigen with alternative molecular forms. 316 78

Mice having the lpr genetic defect bear an expanding lymphoid T-cell population with unusual cell surface characteristics. Using SDS-PAGE analysis, the T cells from lpr mice were shown to have two forms of the T-cell antigen receptor. A conventional (nonreduced) 90-kDa receptor and a lighter 70- to 85-kDa form were both detected. The 70- to 85-kDa antigen receptor was also shown to be present on lpr thymocytes. Only the normal 90-kDa receptor was found in MRL-++ mice. Treatment of the receptor with N-glycanase shows that the 70- to 85-kD form may be a product of abnormal glycosylation. The low-molecular-weight antigen receptor on lpr T cells is unusual and might contribute in some way to the disordered immunoregulation and autoimmunity that occur spontaneously in these mice.
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PMID:T-cell antigen receptor studies in mice expressing the lpr genetic defect. 326 39

The L-selectin, a cell surface C-type lectin, directs lymphocyte traffic to lymph nodes, and contributes to lymphocyte homing to Peyer's patches and to leukocyte interactions with inflamed venules. Here we report that the mucosal vascular addressin MAdCAM-1, a mucosal endothelial adhesion molecule with immunoglobulin- and mucin-like domains, is a facultative ligand for L-selectin. MAdCAM-1 isolated from mesenteric lymph nodes, but not from cultured endothelioma cells, bears N-glycanase-resistant sialic acid-containing carbohydrate which supports adhesion of L-selectin-transfected lymphoid cells under shear. Interacting lymphoid cells display a 'rolling' behaviour similar to the selectin-dependent rolling of neutrophils observed in inflamed venules. MAdCAM-1 is also a ligand for the lymphocyte integrin homing receptor for Peyer's patches, alpha 4 beta 7 (ref. 7), and may be uniquely adapted to support both selectin-mediated lymphocyte rolling and integrin-mediated adhesion and arrest in vivo.
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PMID:L-selectin-mediated lymphocyte rolling on MAdCAM-1. 750 52

We have previously demonstrated that human immunodeficiency virus (HIV) envelope glycoproteins have specific carbohydrate-binding properties for mannosyl/N-acetylglucosaminyl residues presented at high density on a carrier in vitro. Here, we investigated whether HIV envelope glycoprotein gp120 was able to interact with surface membrane carbohydrates of CD4+ cells by means of such lectin-carbohydrate interactions. CD4-free tryptic glycopeptides, prepared from the membrane of CD4+ monocytic U937 cells and partially purified by ConA-agarose affinity chromatography, could be eluted by mannan but not by methyl-alpha-mannose or methyl-alpha-glucose, which strongly suggests that they displayed oligomannosidic structures. These glycopeptides bound in a mannosyl-specific manner to radiolabeled recombinant gp120. Deglycosylation with N-glycanase which, as expected, strongly diminished binding of the glycopeptides to concanavalin A also abolished their interaction with gp120. In addition, the glycopeptides inhibited HIV infection of both U937 and CD4+ lymphoid CEM cells when preincubated with the virus. These findings indicate that, independently of the binding to CD4, mannosyl structures on CD4+ cells may play a role through lectin-carbohydrate interactions in envelope glycoprotein binding to a putative coreceptor(s) of HIV.
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PMID:Inhibition of human immunodeficiency virus infection of CD4+ cells by CD4-free glycopeptides from monocytic U937 cells. 882 18

We have investigated the effect of deglycosylation with peptide-N-glycosidase F (PNGase F) on the sensitivity to inhibition by immune sera of two variants of the Petaluma strain of feline immunodeficiency virus (FIV-Pet), one sensitive to antibody-mediated neutralization because tissue culture adapted and the other, obtained by passaging the previous one in vivo, resistant to neutralization. The partial deglycosylation achieved did not appreciably affect FIV-Pet infectivity for T lymphoid cell cultures and did not increase the susceptibility to serum neutralization of the resistant variant but totally prevented neutralization of the sensitive variant. These finding suggest that the epitopes involved in neutralization of tissue culture-adapted FIV-Pet are effectively recognized by antibody only when the viral surface is properly glycosylated.
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PMID:Effect of enzymatic deglycosylation on feline immunodeficiency virus sensitivity to antibody-mediated neutralization. 949 9

Human FcepsilonRII/CD23 is an approximately 45 kDa type II transmembrane glycoprotein belonging to the C-type animal-lectin family, and has two isoforms (a and b) that only differ in their intracytoplasmic tails. We previously found that in several human and mouse cell lines there were two additional CD23 transcripts (a' and b') lacking the exon 3 that encodes the entire transmembrane segment and a part of cytoplasmic tails. In this study, we analyzed the putative CD23a' and CD23b' products at protein levels and characterized with rabbit polyclonal antibodies against novel amino-acid sequences of the putative CD23a' and CD23b' molecules (anti-CD23a' Ab, anti-CD23b' Ab). Western blots in COS cells transfected with CD23a' or CD23b' cDNA as well as in vitro translation assays showed that the a' and b' CD23 transcripts were translated to about 40 kDa molecules. These 40 kDa molecules were also recognized by a polyclonal antibody against 25 kDa soluble fragment of human CD23. We also found that human cells having mRNAs for CD23a' and CD23b' expressed protein products recognized specifically by anti-CD23a' or anti-CD23b' Ab, respectively. In addition, the CD23a' and CD23b' molecules in transfected COS cells were resistant to Endo H(f) and PNGase F, although these truncated forms as well as the membrane-associated forms had an asparagine residue responsible for the N-linked glycosylation. Taken together, our results show that the a' and b' CD23 transcripts are expressed and translated in human lymphoid cells and that their translated products are retained in the cytoplasm where they might play an unique regulatory role in the expression of the full-length CD23 on the cell surface.
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PMID:Characterization of novel FcepsilonRII/CD23 isoforms lacking the transmembrane (TM) segment in human cell lines. 1068 62

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