1,721,001 research outputs found
Electrophoretic and lectin-binding properties of glycopeptides released from the membrane during "in vitro" aging of human erythrocytes.
No full textDuring in vitro aging of human erythrocytes sialopeptides are lost from the membrane in a process which appears to act on glycophorins. This glycopeptide material can be purified by affinity chromatography on Wheat germ agglutinin-Sepharose, as glycophorin does. The electrophoretic behaviour of the purified material suggests that the glycopeptide comes from the breakdown of the domain of glycophorin exposed on the surface of the membrane. The binding properties toward Phaseolus vulgaris E lectin indicate that the only N-linked sugar chain of glycophorin is present in the sialopeptide released from the membrane; therefore we can argue that the glycophorin breakdown during in vitro aging of red cell takes place beyond the 26th residue of the sequence, and probably quite near the lipid bilayer
Mouse C127 cells transfection with fucosyltransferase Fuc-TIII express masked Lewis X but not Lewis X antigen
No full textDifferential expression of beta1,3galactosyltransferase in human colon cells derived from adenocarcinomas or normal mucosa
No full textRe-evaluation of the structural integrity of red-cell glycoproteins during aging in vivo and nutrient deprivation
No full textResults presented in this paper show that removal of white-cell contaminations from human red blood cells by filtration through cellulose [Beutler, West & Blume (1976) J. Lab. Clin. Med. 88, 328-333] is a necessity whenever red cells are incubated at elevated temperatures or haemolysed after density separation. Omission of this precaution results in proteolysis of sialoglycoproteins in membranes from less-dense (young), but not dense (old), subpopulations. This proteolytic damage occurs during haemolysis of the cytoplasmic domain of glycophorin. A different type of proteolysis occurs if white-cell-contaminated red cells are incubated in the absence of glucose at elevated temperatures. Red cells release sialoglycopeptides. This process is stimulated by Ca2+ ions and is accompanied by the release of vesicles that differ from spectrin-free vesicles [Lutz, Liu & Palek (1977) J. Cell Biol. 73, 548-560]. This sialoglycopeptide release is dependent on white-cell contamination and is not required for the release of spectrin-free vesicles
beta 1,3-Galactosyltransferase beta 3Gal-T5 acts on the GlcNAcbeta 1-->3Galbeta 1-->4GlcNAcbeta 1-->R sugar chains of carcinoembryonic antigen and other N-linked glycoproteins and is down-regulated in colon adenocarcinomas.
No full textWe attempted to determine whether beta1,3-galactosyltransferase beta3Gal-T5 is involved in the biosynthesis of a specific subset of type 1 chain carbohydrates and expressed in a cancer-associated manner. We transfected Chinese hamster ovary (CHO) cells expressing Fuc-TIII with beta3Gal-T cDNAs and studied the relevant glycoconjugates formed. beta3Gal-T5 directs synthesis of Lewis type 1 antigens in CHO cells more efficiently than beta3Gal-T1, whereas beta3Gal-T2, -T3, and -T4 are almost unable to direct synthesis. In the clone expressing Fuc-TIII and beta3Gal-T5 (CHO-FT-T5), sialyl-Lewis a synthesis is strongly inhibited by swainsonine but not by benzyl-alpha-GalNAc, and sialyl-Lewis x is absent, although it is detected in the clones expressing Fuc-TIII and beta3Gal-T1 (CHO-FT-T1) or Fuc-TIII and beta3Gal-T2 (CHO-FT-T2). Endo-beta-galactosidase treatment of N- glycans prepared from clone CHO-FT-T5 releases (+/-NeuAcalpha2-->3)Galbeta1-->3[Fucalpha1-->4]GlcNAcbeta1-->3Gal but not GlcNAcbeta1-->3Gal or type 2 chain oligosaccharides, which are found in CHO-FT-T1 cells. This result indicates that beta3Gal-T5 expression prevents poly-N-acetyllactosamine and sialyl-Lewis x synthesis on N-glycans. Kinetic studies confirm that beta3Gal-T5 prefers acceptors having the GlcNAcbeta1-->3Gal end, including lactotriosylceramide. Competitive reverse transcriptase mediated-polymerase chain reaction shows that the beta3Gal-T5 transcript is expressed in normal colon mucosa but not or poorly in adenocarcinomas. Moreover, recombinant carcinoembryonic antigen purified from a CHO clone expressing Fuc-TIII and beta3Gal-T5 reacts with anti-sialyl-Lewis a and carries type 1 chains on oligosaccharides released by endo-beta-galactosidase. We conclude that beta3Gal-T5 down-regulation plays a relevant role in determining the cancer-associated glycosylation pattern of N-glycans
Could proteomics become a future useful tool to shed light on the mechanisms of rare neurodegenerative disorders?
Full text linkVery often the clinical features of rare neurodegenerative disorders overlap with those of other, more common clinical disturbances. As a consequence, not only the true incidence of these disorders is underestimated, but many patients also experience a significant delay before a definitive diagnosis. Under this scenario, it appears clear that any accurate tool producing information about the pathological mechanisms of these disorders would offer a novel context for their precise identification by strongly enhancing the interpretation of symptoms. With the advent of proteomics, detection and identification of proteins in different organs/tissues, aimed at understanding whether they represent an attractive tool for monitoring alterations in these districts, has become an area of increasing interest. The aim of this report is to provide an overview of the most recent applications of proteomics as a new strategy for identifying biomarkers with a clinical utility for the investigation of rare neurodegenerative disorders
Protection of rat gastric mucosa against ethanol injury by the new synthetic prostaglandin MDL 646.
No full textOral administration to fasted rats of absolute ethanol produces extensive necrotic lesions of gastric mucosa as well as a massive leakage of proteins and mucus glycoproteins into gastric lumen. When the new synthetic prostaglandin MDL 646, belonging to the PGE1 series, is administered intragastrically (2 or 10 micrograms/kg) 30 min before ethanol administration, a significant protection of rat gastric mucosa against alcohol injury is observed
The effect of cornea proteoglycans on liposome peroxidation
No full textProteoglycans (PGs) from bovine cornea showed a protective effect on liposome peroxidation induced by Fe2+. Both chondroitin sulfate, dermatan sulfate-containing PG (CS,DS-PG) and keratan sulfate-containing PG (KS-PG) inhibited thiobarbituric acid-reactive substance formation when incubated with liposomes and Fe2+, CS,DS-PG being more effective than KS-PG. The native structure of PGs contributed markedly to antioxidant activity. Papain digestion of core protein reduced the protective effect of CS,DS-PG, whereas it abolished completely that of KS-PG. Apparently only hexuronate-containing glycosaminoglycan (GAG) chains may exert a significant antioxidant activity and this was confirmed using standard GAGs. Quasielastic laser light scattering was used to evaluate the structural consequence of peroxidative damage induced by Fenton reagent on liposomes. After exposure to the free-radical-generating system, a bimodal distribution of liposomes was observed, probably depending on the loss of native structure and fragmentation. Both CS,DS-PG and KS-PG prevented liposome breakdown. Again, free KS chains were ineffective against liposome damage, whereas DS and CS maintained the normal distribution of liposome size. These data support the hypothesis that PGs may represent part of the antioxidant mechanisms of organisms and suggest that modifications of PG content and/or composition might affect tissue sensitivity to oxidative stress
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