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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two lectin-resistant mutants derived from a polarized epithelial cell line have been described (Meiss, H.K., Green, R.F., and Rodriguez-Boulan, E.J. (1982) Mol. Cell. Biol. 2, 1287-1294). One of these mutants, the Madin-Darby canine kidney strain II cell line resistant to Ricinus communis agglutinin (MDCKII-RCAr), has been further characterized, and the biochemical defect leading to its altered phenotype has been determined. MDCKII-RCAr cells are shown to be enriched in cell-surface glycoconjugates bearing terminal N-acetylglucosamine residues by in vitro exogalactosylation and by labeling with fluorescent lectins. Binding assays with a sialic acid-specific lectin reveal a 70-75% reduction in sialylation of cell-surface glycoconjugates. The defect is pleiotropic in nature, affecting glycoproteins as well as glycosphingolipids. Analysis of glycosphingolipids shows a strong reduction of galactose-containing glycosphingolipids. Almost 90% of the glycosphingolipids are identified as glucosyl-ceramide. The mutant is not deficient in galactosyl- and sialytransferase activities. However, Golgi vesicles isolated from MDCKII-RCAr cells translocate UDP-galactose at only 2% of the rate observed for vesicles from wild-type MDCKII cells. The deficiency is specific, because translocation rates of UDP-N-acetylglucosamine and CMP-sialic acid are comparable for vesicles isolated from MDCKII-RCAr cells and wild-type cells. Despite the inability to translocate UDP-galactose into the lumen of the Golgi apparatus, MDCKII-RCAr cells are able to form monolayers with normal apical and basolateral polarity as shown by plasma membrane domain-restricted exogalactosylation.
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PMID:A polarized epithelial cell mutant deficient in translocation of UDP-galactose into the Golgi complex. 314 4

Several reports have described the destruction of the N-linked oligosaccharides on glycoprotein hormones by hydrogen fluoride treatment and have noted the accompanying marked reduction, or complete loss, in biological activity. This has led to the concept that the oligosaccharides have an obligatory role in glycoprotein hormone steroidogenic function. Using a less radical and more complete method for removing sugar units, endoglycosidase treatment and ovine LH (oLH) and human LH (hLH) as examples, we examined the role of oligosaccharides in hormone function. Ovine LH and hLH were digested with endoglycosidase F. After treatment cleavage of oligosaccharides was demonstrated by compositional studies, greater than 87% cleavage was demonstrated and only N-acetylglucosamine or N-acetylglucosamine-Fucose shown to remain attached to the peptide, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (appropriate size change) and by chromatofocusing (appearance of a single basic peak). Biological activities and relative potencies of preparations were then assessed in an in vitro assay, in which the ability of samples to promote testosterone production by testicular interstitial cells was measured. Although endoglycosidase F treatment reduced relative potencies 2- to 3-fold in the bioassay, (possibly in part due to subunit dissociation) it did not lessen abilities to induce maximal testosterone response (that of native hLH and oLH). These findings contrast with those obtained from hydrogen fluoride studies and indicate that the oligosaccharides, per se, do not play an obligatory role in the steroidogenic activity of LH.
Mol Endocrinol 1987 Sep
PMID:Significant steroidogenic activity of luteinizing hormone is maintained after enzymatic removal of oligosaccharides. 315 65

Serum amyloid P component (SAP) is a normal human serum protein with pentraxin structure that has morphological and immunochemical identity to the amyloid P component found in normal tissue and amyloid deposits. In the presence of calcium, SAP binds to certain complex polysaccharides, including agarose and zymosan. While the binding of SAP to agarose involves interaction with a galactose pyruvate acetal, the ligand in zymosan has not been defined. In the present study we determined that SAP binds to ligand(s) in a soluble extract of zymosan prepared by alkaline hydrolysis, which contains the mannose oligosaccharide sequences alpha DMan1----3DMan and alpha DMan1----6DMan. SAP did not bind to the alkali-insoluble fraction of zymosan, which is predominantly a glucan polymer, and its binding to zymosan extract which had been absorbed with concanavalin A was markedly reduced, suggesting that mannose residues are involved in the binding of SAP to zymosan. We also demonstrated that SAP binds to the glycoproteins ovalbumin, thyroglobulin, beta-glucuronidase and C3bi, which contain mannose-terminated sequences, while it did not bind to native and desialized preparations of ovomucoid, alpha 1-acid glycoprotein and glycophorin, which lack terminal mannose residues. SAP did not bind to pneumococcal C polysaccharide or to N-acetylglucosamine oligosaccharides covalently linked to a protein carrier. The binding of SAP to ligand(s) in zymosan extract or ovalbumin was inhibited by the preincubation of SAP with either zymosan extract or ovalbumin glycopeptides, both of which share similar mannose oligosaccharide sequences. All of the SAP binding reactions required calcium, were maximal at approximately 1 mM calcium, and gave similar results whether purified SAP or SAP in serum was used. These findings indicate that mannose-terminated oligosaccharides of polysaccharides and glycoproteins represent a new class of ligands for SAP and suggest that SAP may function as a mannose-binding protein.
Mol Immunol 1988 Sep
PMID:Evidence that serum amyloid P component binds to mannose-terminated sequences of polysaccharides and glycoproteins. 321 Nov 59

Detergent solubilized extracts of 125Iodogen surface labelled adult Loa loa revealed a relatively simple profile consisting of a strongly labelled molecule at 29-31 kDa and weakly labelled molecules at 14.5, 17, 21, 23, 34, 58, and 86 kDa. Residents of a L. loa endemic zone were assessed clinically and parasitologically and classified as microfilaremic, amicrofilaremic with documented ocular passage of adult worms, or 'resistant' subjects without any signs of infection. Sera from these subjects were used to identify L. loa adult surface antigens. All 'resistant' sera immunoprecipitated the 29-31 kDa antigen although some were more strongly reactive than others. The amicrofilaremic sera strongly immunoprecipitated the 29-31 kDa antigen, whereas microfilaremic sera reacted weakly or not at all with this antigen. Longer exposures of immunoprecipitates of strongly reactive sera revealed the recognition of additional antigens of 86, 44, 34, 23, 21, 17 and 14.5 kDa. Studies with heterologous sera demonstrated that these antigens contain cross-reactive epitopes which are restricted to filarial parasites. Biochemical characterization of the predominant 29-31 kDa antigen showed that it bound concanavalin A, was sensitive to proteases, and its antigenicity was resistant to heat but sensitive to periodate and endo-beta-N-acetylglucosaminidase H. These observations suggest that it is a glycoprotein containing mannose and N-acetylglucosamine residues and that the carbohydrate moiety is important for antibody binding. The importance of the 29-31 kDa glycoprotein in the immunobiology of loaiasis is suggested by the finding that resistant and infected amicrofilaremic individuals have strongly reactive IgG antibodies to this antigen.
Mol Biochem Parasitol 1988 Dec
PMID:The identification and partial characterization of an immunodominant 29-31 kilodalton surface antigen expressed by adult worms of the human filaria Loa loa. 322 11

The effects of glycoproteins and neoglycoproteins specific for liver and macrophage membrane lectins on both the cellular attachment and the clearance of Leishmania donovani from hamster blood were investigated. Although the inhibition pattern of in vitro cellular attachment studies indicates the involvement of both galactose and mannose/N-acetylglucosamine receptors, the in vivo blood clearance of the parasites was inhibited only by glycoproteins and neoglycoproteins specific for mannose/N-acetylglucosamine receptors. The inhibitory effects on blood clearance were abolished by pretreating the parasites with tunicamycin, an inhibitor of protein glycosylation. These results indicate that the mannose/N-acetylglucosamine hepatic lectin recognizes specific sugars on the parasite surface and is important to the promastigote during the early stages of infection.
Mol Biochem Parasitol 1988 Feb
PMID:Role of mannose/N-acetylglucosamine receptors in blood clearance and cellular attachment of Leishmania donovani. 337 26

The asparagine-linked oligosaccharide structures of chronic lymphocytic leukemia cells (CLL) were studied by sequential lectin affinity chromatography. Glycopeptides were isolated from a Concanavalin A (ConA)-binding glycoprotein fraction prepared from a soluble CLL extract. This fraction, which contained 1.8% of the proteins present in the soluble extract, greater than 30 polypeptides revealed by SDS-PAGE analysis, and known cell surface antigens such as HLA-DR and p85 glycoprotein, must include a major proportion of the glycoproteins of the CLL cells. Glycopeptides were prepared by digestion with pronase, were separated into four pools (A-D) by Bio-Gel P-6 filtration and were radiolabeled by N-14C-acetylation. Glycopeptide pools C and D (0.45 less than Kd less than 0.77) were 95-100% bound to ConA-Sepharose and 7-12% bound to Lens culinaris (Lens)-Sepharose, but did not interact with any of the other lectins tested, suggesting major amounts of high mannose structures and minor amounts of fucosylated biantennary complex structures with terminal GlcNAc on the Man alpha 1-6 arm. Structures with greater than 3 branches were suggested for pools A and B (0 less than Kd less than 0.44) which were 34-65% unbound to ConA-Sepharose and 37-40% bound to Lens-Sepharose. Analysis of the ConA-unbound glycopeptides on RCA-Agarose before and after acid hydrolysis indicated variable amounts of terminal galactose and sialic acid residues. Major components of pool A were structures with terminal GlcNAc on all branches (22%) and fully sialylated structures (20%). In pool B, 20% of the radioactivity interacted with L-Phaseolus vulgaris agglutinin (PHA)-Agarose and with Ricinus communis (RCA)-Agarose, indicative of a fully galactosylated triantennary structure with branches at C-2 and C-6 of the Man alpha 1-6 arm. Half of the L-PHA-interacting material also bound to Lens-Sepharose, indicative of a core fucose residue. A fully galactosylated biantennary complex structure in pool A (13%) was identified by weak binding to ConA-Sepharose and strong interaction with RCA-Agarose. The presence of the polylactosamine sequence (Gal beta 1-4GlcNAc beta 1-3)n on this structure was suggested by a sialic acid independent interaction with wheat germ agglutinin (WGA)-Agarose. A sialic acid dependent WGA-interaction was observed in the ConA-unbound glycopeptides of pool A (5%). Some of the structures identified in this study may be associated with the malignant CLL phenotype and/or with a distinct stage of B cell differentiation.
Mol Immunol 1987 Aug
PMID:Analysis of asparagine-linked oligosaccharide structures of chronic lymphocytic leukemia cells. 349 86

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

An enzymatic assay using Micrococcus lysodeikticus as substrate had shown that hen egg-white lysozyme (HEL), complexed to the specific monoclonal antibody D1.3, was enzymatically inactive. However, a crystallographic study of the HEL-Fab D1.3 complex at 2.8 A resolution showed that Fab D1.3 is bound to the enzyme at a region remote from the catalytic site, and that no significant conformational change had occurred in the bound lysozyme. To resolve this apparent discrepancy, oligomers of N-acetylglucosamine, containing an average of six residues and which should not be sterically hindered by the monoclonal antibody, were used as substrate in enzyme assays. In these assays lysozyme complexed to antibody D1.3 retained enzymatic activity, thus supporting the results of the crystallographic study and indicating no major conformational change or rigidification of its structure.
Mol Immunol 1987 Mar
PMID:Lysozyme bound to the D1.3 monoclonal antibody retains enzymatic activity in assays using N-acetylglucosamine oligomers as substrate. 361 17

Uteroferrin is a purple iron-containing acid phosphatase secreted by the porcine uterus under the influence of the hormone, progesterone. It is synthesized by the glandular epithelial cells of the uterine endometrium and during pregnancy is taken up by specialized structures (areolae) opposite each uterine gland. Uteroferrin is then released into the fetal circulation and cleared by the liver or fetal kidney. A major role in iron transport to the fetus has been proposed. Uteroferrin, as purified from uterine secretions of pigs, possesses mainly high mannose (predominantly Man5 and Man6) chains. These oligosaccharide chains of uteroferrin appear to be responsible for its binding and uptake by reticuloendothelial cells of the fetal liver which is the major site of erythropoiesis of the fetus. Uteroferrin, although implicated in transplantal iron transport, also possesses many of the properties of a lysosomal enzyme and, when newly synthesized, carries the so-called lysosomal recognition marker, mannose 6-phosphate. The phosphate group is masked by a covering N-acetylglucosamine residue, a feature which may account for its secretion rather than retention within lysosomes. Evidence is also presented that the oligosaccharide chains of newly synthesized uteroferrin are larger than those of the mature form and are trimmed after secretion. The phosphate group is also removed. It is not clear whether uteroferrin carbohydrate is implicated in the movement of the glycoprotein across the placenta as well as its uptake by the fetal liver.
Mol Cell Biochem
PMID:Possible function of carbohydrate on glycoproteins secreted by the pig uterus during pregnancy. 382 22

The carbohydrate composition of the second, third and fifth components of human complement (C2, C3 and C5) and of factors B and D was determined employing gas-chromatographic and mass-spectrometric methods. C2 was found to contain 15.9% carbohydrate composed of fucose, galactose, mannose, N-acetylglucosamine and N-acetylneuraminate (approximate molar ratio 1:4:9:9:4). N-acetylglucosamine and mannose (approximate molar ratio 1:4), amounting to 1.7% of the mass of the molecule, were the only monosaccharides detected in C3. C5 contained 3.8% carbohydrate composed of galactose, mannose, N-acetylglucosamine and N-acetylneuraminate (approximate molar ratio 2:4:4-5:2). The carbohydrate moiety of B consisted of fucose, galactose, mannose, N-acetylglucosamine and N-acetylneuraminate (molar ratio 1:2:3:4:2). The total carbohydrate content of B was estimated at 8.6%. In addition to these monosaccharides, glucose (0.4-0.9%) was also detected in all preparations analysed. Glucose was the only sugar detected in D.
Mol Immunol 1985 Feb
PMID:Carbohydrate composition of the second, third and fifth components and factors B and D of human complement. 384 1


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