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Query: UNIPROT:P06889 (Mol)
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Diffraction-quality crystals have been obtained for complexes of each of the major wheat germ agglutinin (WGA) isolectins with the tryptic sialoglycopeptide T-5 from the WGA red cell receptor glycophorin A. This octa-glycopeptide possesses a Thr-linked carbohydrate moiety (GalNAc(NeuNAc)-Gal-NeuNAc) with specificity for the WGA binding site. The crystals belong to the orthorhombic space group P2(1)2(1)2 and have unit cell dimensions: a = 112.2 A, b = 51.0 A, c = 63.5 A (isolectin 1); a = 109.0 A, b = 52.3 A, c = 62.4 A (isolectin 2). There are two monomer complexes in each asymmetric unit.
J Mol Biol 1987 Mar 20
PMID:Preliminary X-ray diffraction results on co-crystals of wheat germ agglutinin with a sialoglycopeptide from the red cell receptor glycophorin A. 361 12

Four monoclonal antibodies (MAbs) directed against the P1 blood group antigen were produced by hybridomas obtained from mouse immunized with turtle-dove avomucoid. One of the MAb (154 IX B6) selected as a blood typing reagent agglutinated native P1 and Pk1 red cells with a high titer but was inactive against native P2, Pk2 and p erythrocytes. After papain treatment the reactivity towards P1 and Pk1 erythrocytes was enhanced whereas p erythrocytes remained unreactive. A weak cross-reactivity of the MAb with the Pk antigen was suspected since enzyme-treated Pk2 erythrocytes became significantly agglutinated. Further analysis of the antibody specificity was established by binding studies using neutral glycolipids prepared from P1 and P2 erythrocytes, affinity immunoabsorbents carrying known oligosaccharide structures and hapten inhibition with synthetic oligosaccharides. The MAb bound weakly to the Gal alpha 1-4Gal structure common to P1 and Pk antigens but had a marked preference for the P1 determinant (Gal alpha 1-4 Gal beta 1-4 GlcNAc) and the binding was abolished by prior treatment of oligosaccharide antigens by alpha(not beta)-galactosidase, which supports evidence that a terminal alpha-galactose residue is involved in the blood group P1 and Pk specificities. The MAb has a slightly broader specificity than the human anti-P1 counterpart but can be used safely for routine blood typing.
Mol Immunol 1987 Feb
PMID:Characterization of a murine monoclonal antibody specific for the human P1 blood group antigen. 361 10

Monoclonal antibodies A5 and C6 have been reported previously to recognize developmentally regulated determinants involving N-acetyllactosamine [Fenderson B. A., O'Brien D. A., Millette C. F. and Eddy E. M. (1984) Devl Biol. 103, 117-128]. In the present study, the specificity of these antibodies was determined by solid-phase radioimmunoassay and by thin-layer chromatography immunostaining using purified glycolipid standards. Antibody A5 recognized N-acetyllactosamine (type 2 chain; Gal beta 1----4GlcNAc beta 1----3R), irrespective of branching status. In contrast antibody C6 recognized the binary N-acetyllactosamine structure carried on lactoisooctaosylceramide. Antibody C6 did not react with sialosyl or alpha-galactosyl derivatives of the isooctaosyl structure, including human G10, G8 and bovine G9. Thus, unlike other anti-I antibodies, C6 provides a specific probe for both branching status and absence of terminal chain modification. Monoclonal antibodies A5, C6 and anti-I(Ma) were used to investigate glycosylation changes associated with oncogenic transformation. In contrast to results with lectins, these antibodies preferentially labeled the major glycoproteins of SV40-transformed human embryonic lung fibroblasts, including GP80, GP180, GP200 and GP250. The results suggest that increased expression of unsubstituted polylactosamine core structure at the cell surface follows SV40-transformation.
Mol Immunol 1986 Jul
PMID:A monoclonal antibody defining a binary N-acetyllactosaminyl structure in lactoisooctaosylceramide (IV6Gal beta 1----4GlcNAcnLc6): a useful probe for determining differential glycosylation patterns between normal and transformed human fibroblasts. 379 23

The sequence of N-linked oligosaccharides of differentially glycosylated murine I-Ak alpha-(alpha 2- and alpha 3-) and beta-chains was determined. I-Ak beta-chains predominantly bear a biantennary complex oligosaccharide with a core fucose, and with the peripheral sequence SA----Gal----GlcNAc----Man. The I-Ak alpha-chain has two N-linked glycosylation sites at Asn-82 and Asn-122. When Lubrol-insoluble alpha 3-chains are examined they are found to bear high-mannose oligosaccharides of either the Man9GlcNAc2 or Man8GlcNAc2 type at both sites. When Lubrol-soluble alpha 2-chains are examined, in about 85% of the molecules the Asn-82 site bears a biantennary complex oligosaccharide with core fucose, and with the peripheral sequence SA----Gal----GlcNAc----Man. Interestingly, the Asn-122 site bears a variety of structures. In about 50% of the molecules, the structure at Asn-122 is a biantennary complex oligosaccharide without core fucose and with the peripheral sequence SA----Gal----GlcNAc----Man. In addition, it can bear other complex structures which we did not define further. The apparently restricted addition of fucose to the oligosaccharide at the alpha-Asn-82 site, even when both alpha-sites bear biantennary complex structures with the same peripheral sequence, is a feature unique to this system. The unusual variety of structures present at the alpha-Asn-122 site may indicate differential processing in different cell types.
Mol Immunol 1985 Feb
PMID:Structural characterization of murine Ia antigen N-linked oligosaccharides and localization of specific structures to two unique alpha-chain glycosylation sites. 385 97

Antibodies formed in rabbits to synthetic glycoproteins with the disaccharide structure beta-D-Gal-(1-3)-D-GalNAc, the carbohydrate moiety of desialylated glycophorin A, were investigated for their carbohydrate specificity by hemagglutination techniques and radioimmunoassay. The synthetic disaccharide was coupled to human serum albumin as carrier protein using different spacer groups and different configurations of the disaccharide spacer linkage. Radioimmunological inhibition experiments using a number of different derivatives of the carbohydrate group as inhibitors revealed a significant specificity of the antibodies for the oligosaccharide structure. However, the nature of the conjugation of the disaccharide to the carrier protein was found to be important for defining the specificity of the antibodies. Furthermore the arrangement of the hapten groups in the synthetic antigen had an important influence on the antigen-antibody reaction. No cross-reactions were observed between asialo-glycophorin A and the different synthetic antigens. Synthetic antigens provide a valuable tool for generating carbohydrate-specific antibodies. However, if the synthetic hapten molecule is small compared to the combining site of antibodies, the specificity of the immunological reaction is significantly influenced by the synthetic spacer arm or even the carrier protein.
Mol Immunol 1985 Dec
PMID:Study on the carbohydrate specificity of antibodies formed in rabbits to synthetic glycoproteins with the carbohydrate structure of asialo-glycophorin A. 393 24

The I- and i-antigen activities of chemically synthesized, linear oligosaccharides of the neolacto series containing one, two or three N-acetyllactosamine (Gal beta 1----4GlcNAc) units have been tested by inhibition of binding of five anti-i and eight anti-I monoclonal antibodies to radioiodinated I- and i-active glycoproteins. The inhibitory activities of the milk oligosaccharides lacto-N-neotetraose (Gal beta 1----4GlcNAc beta 1----3Gal beta 1----4Glc) and lacto-N-tetraose (Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc) have also been determined. The results clearly show that: (a) the determinants that best fit the combining sites of anti-i antibodies are at least hexasaccharides of the neolacto series, (b) linear tetra- and hexasaccharides of the neolacto series can strongly inhibit the binding of anti-I antibodies of group 2 which are known to be primarily directed at the repeating Gal beta 1----4GlcNAc beta 1----3 domains of branched neolacto sequences, (c) the beta- but not the alpha-methyl anomer of the glycoside Gal beta 1----4GlcNAc beta 1-O-Me inhibits the binding of anti-I antibodies of group 1 which recognise the branch point sequence Gal beta 1----4GlcNAc beta 1----6-, (d) the reactivity of the beta-methylglycoside is impaired if the sequence is further elongated as in Gal beta 1----4GlcNAc beta 1----3Gal beta 1----4GlcNAc beta-O-Me, and (e) lacto-N-tetraose has no inhibitory activity with any of the anti-i or anti-I antibodies tested.
Mol Immunol 1984 Nov
PMID:Further studies of the specificities of monoclonal anti-i and anti-I antibodies using chemically synthesized, linear oligosaccharides of the poly-N-acetyllactosamine series. 608 47

The intracellular pathways taken by galactose-terminal glycoproteins were examined following endocytosis by the asialoglycoprotein receptor in monolayers of the human hepatoma cell line, Hep G2. In addition to a pathway leading to lysosomal degradation, single cohort kinetics revealed that up to 28% of surface-bound and internalized 125I-asialoorosomucoid (ASOR) eventually returned undegraded to the extracellular medium over 6 hr in the presence or absence of free ASOR in the exocytosis medium. This reappearance of ligand in the exocytosis medium represented a constant fraction of surface bound and internalized 125I-ASOR, and followed pseudo-first order kinetics with t1/2 = 84 min (long transit pool). Under conditions of enhanced ligand-receptor dissociation (incubation with 100 mM N-acetylgalactosamine (GalNAc), at least 50% of initially internalized 125I-ASOR returned to the cell surface as ligand-receptor complexes, followed by dissociation of free ligand into the exocytosis medium. This rapid transit pool of ligand also displayed pseudo-first order kinetics with t1/2 = 24 min. Exocytosis of 125I-Gal-cytochrome c, a synthesized ligand displaying rapid dissociation from the asialoglycoprotein receptor (ASGP-R), paralleled the kinetics of the rapid transit pool of 125I-ASOR (t1/2 = 28 min). Furthermore, in addition to spontaneous dissociation from ASPG-R following return to the cell surface, studies conducted in saponin-permeabilized monolayers support the return of free intracellular 125I-Gal-cytochrome c to the cell surface during exocytosis. The rapid transit pool of ligand was insensitive to inhibition by 10 mM sodium azide or 0.1 mM primaquine. In contrast, the long transit pool destined for exocytosis was inhibited 50% by 10 mM sodium azide, but insensitive to inhibition by 0.1 mM primaquine. These data suggest that, following internalization by the ASGP-R, a major pathway of ligand movement includes the rapid return of ligand-receptor complexes and/or free ligand to the cell surface. Return of ligand-receptor complexes or free ligand to the cell surface occurs prior to an acidic sorting compartment, can involve multiple cycles of return to the cell surface, and may involve passage through other nonlysosomal intracellular organelles.
Mol Pharmacol 1984 Nov
PMID:Cellular pathways of galactose-terminal ligand movement in a cloned human hepatoma cell line. 609

This report demonstrates that a marker of human embryonic endoderm and embryonal carcinoma cells recognized by a hybridoma antibody FC 10.2, involves Type 1 blood group chains with the sequence Gal beta 1 leads to 3G1cNAc beta 1 leads to 3Gal beta 1 leads to 4G1c. This conclusion has been reached from antigenic analyses of meconium, ovarian cyst glycoproteins, oligosaccharides and glycolipids having Type 1 or Type 2 blood group chains. From knowledge of saccharide sequences and blood group related antigens in gastrointestinal tissues of man, we deduce that the 'disappearance' of FC 10.2 antigen from the normal, differentiated cells of the adult may result from masking by additional glycosylations or other substitutions.
Mol Immunol 1983 Jun
PMID:A marker of human foetal endoderm defined by a monoclonal antibody involves Type 1 blood group chains. 619 30

The insertion sequence IS2 is a small transposable element of Escherichia coli that lacks any known genetic markers. Insertion of this element in one orientation (I) within bacterial operons blocks expression of downstream genes. In the other orientation (II), IS2 has been associated with the constitutive expression of genes distal to its insertion, suggesting that IS2 might contain promoters directing transcription of IS2(II) into other genes. To test the transcription potential of IS2, we have transcribed in vitro DNA templates from gal3, a Gal- allele in which an IS2(I) is inserted between the gal promoter and the gal genes. We have detected two IS2-specific RNAs which initiate from promoters within IS2 and are transcribed in orientation II (away from the galETK genes). Though the presence and orientation of these promoters suggests that they could be responsible for the constitutive expression of genes adjacent to an IS2(II) element, an alternative role could be for transcription of IS2-encoded genes. Although IS2(I) insertions normally block expression of adjacent genes, certain altered (e.g. mutant) IS2(I) sequences lead to the constitutive expression of downstream genes. We have transcribed DNA templates from galwc5 and galc331, which are Galc alleles that contain altered IS2(I) insertions within the gal operon. For each allele, we have detected two gal-directed transcripts initiating within the IS2 sequence. These RNAs are not detected upon transcription of the unaltered IS2(I) DNA and the promoters arise as a direct consequence of the IS2(I) alterations. This result suggests that these promoters detected in vitro are responsible for the Galc phenotype of these alleles.
J Mol Biol 1983 Sep 05
PMID:Specific in vitro transcription of the insertion sequence IS2. 619 5

The GAL4 gene positively regulating the expression of the gene cluster GAL7-GAL10-GAL1 in the yeast Saccharomyces cerevisiae was isolated for its ability to suppress a recessive mutation in that gene. When the isolated gene was incorporated into a multi-copy plasmid, the GAL cluster genes in the host chromosome partially escaped the normal control; a yeast that harbors the plasmid bearing the GAL4 gene synthesized the galactose-metabolizing enzymes encoded by the GAL cluster genes at a low but significant level in the absence of galactose. If the GAL7 gene was amplified along with GAL4 on the multi-copy plasmid, the constitutive synthesis of Gal-1-P uridylyl transferase encoded by GAL7 was further pronounced and the enzyme activity reached the level of the fully induced wild-type yeast. Such an escape synthesis of the GAL enzymes was not detected if GAL4 or both GAL4 and GAL7 were carried by a single-copy plasmid. The results suggest that the escape synthesis of GAL enzymes observed in the GAL4-amplified yeast was a consequence of overproduction of the GAL4 protein. The GAL80 gene negatively regulating the GAL cluster genes was also isolated, and when amplified together with GAL4, no escape synthesis of the GAL enzymes was observed, suggesting that the balanced synthesis of two regulatory proteins was essential to maintain the repressed state of the GAL cluster genes.
Mol Gen Genet 1983
PMID:Regulation of expression of the galactose gene cluster in Saccharomyces cerevisiae. Isolation and characterization of the regulatory gene GAL4. 635 Aug 27


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