| [C@H]1([C@@H]([C@H]([C@H]([C@H](O1)CO)O)O)NC(=O)C)* |
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epitope
The biological role played by a material entity when bound by a receptor of the adaptive immune system. Specific site on an antigen to which an antibody binds.
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View more via ChEBI Ontology
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Outgoing
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N-acetyl-α-D-galactosaminyl group
(CHEBI:88142)
has role
epitope
(CHEBI:53000)
N-acetyl-α-D-galactosaminyl group
(CHEBI:88142)
is a
N-acetyl-D-galactosaminyl group
(CHEBI:21507)
N-acetyl-α-D-galactosaminyl group
(CHEBI:88142)
is substituent group from
N-acetyl-α-D-galactosamine
(CHEBI:40356)
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Incoming
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α-L-Fuc-(1→2)-[α-D-GalNAc-(1→3)]-β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-α-D-Gal-yl group
(CHEBI:140186)
has part
N-acetyl-α-D-galactosaminyl group
(CHEBI:88142)
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2-acetamido-2-deoxy-α-D-galactopyranosyl
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2-acetamido-2-deoxy-α-D-galactopyranosyl group
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CBN
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α-GalNAc-R
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ChEBI
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N-acetyl-β-D-galactosaminyl-R
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ChEBI
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N-acetyl-D-galactosaminyl-R
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ChEBI
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terminal α-linked GalNAc
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ChEBI
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Breiman A, Ruvoën-Clouet N, Deleers M, Beauvais T, Jouand N, Rocher J, Bovin N, Labarrière N, El Kenz H, Le Pendu J (2021)
Low Levels of Natural Anti-α-<i>N</i>-Acetylgalactosamine (Tn) Antibodies Are Associated With COVID-19.
Frontiers in microbiology 12, 641460 [PubMed:33643275]
[show Abstract]
Human serum contains large amounts of anti-carbohydrate antibodies, some of which may recognize epitopes on viral glycans. Here, we tested the hypothesis that such antibodies may confer protection against COVID-19 so that patients would be preferentially found among people with low amounts of specific anti-carbohydrate antibodies since individual repertoires vary considerably. After selecting glycan epitopes commonly represented in the human anti-carbohydrate antibody repertoire that may also be expressed on viral glycans, plasma levels of the corresponding antibodies were determined by ELISA in 88 SARS-CoV-2 infected individuals, including 13 asymptomatic, and in 82 non-infected controls. We observed that anti-Tn antibodies levels were significantly lower in patients as compared to non-infected individuals. This was not observed for any of the other tested carbohydrate epitopes, including anti-αGal antibodies used as a negative control since the epitope cannot be synthesized by humans. Owing to structural homologies with blood groups A and B antigens, we also observed that anti-Tn and anti-αGal antibodies levels were lower in blood group A and B, respectively. Analyses of correlations between anti-Tn and the other anti-carbohydrates tested revealed divergent patterns of correlations between patients and controls, suggesting qualitative differences in addition to the quantitative difference. Furthermore, anti-Tn levels correlated with anti-S protein levels in the patients' group, suggesting that anti-Tn might contribute to the development of the specific antiviral response. Overall, this first analysis allows to hypothesize that natural anti-Tn antibodies might be protective against COVID-19. | Jeyakanthan M, Tao K, Zou L, Meloncelli PJ, Lowary TL, Suzuki K, Boland D, Larsen I, Burch M, Shaw N, Beddows K, Addonizio L, Zuckerman W, Afzali B, Kim DH, Mengel M, Shapiro AM, West LJ (2015)
Chemical Basis for Qualitative and Quantitative Differences Between ABO Blood Groups and Subgroups: Implications for Organ Transplantation.
American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons 15, 2602-2615 [PubMed:26014598]
[show Abstract]
Blood group ABH(O) carbohydrate antigens are carried by precursor structures denoted type I-IV chains, creating unique antigen epitopes that may differ in expression between circulating erythrocytes and vascular endothelial cells. Characterization of such differences is invaluable in many clinical settings including transplantation. Monoclonal antibodies were generated and epitope specificities were characterized against chemically synthesized type I-IV ABH and related glycans. Antigen expression was detected on endomyocardial biopsies (n = 50) and spleen (n = 11) by immunohistochemical staining and on erythrocytes by flow cytometry. On vascular endothelial cells of heart and spleen, only type II-based ABH antigens were expressed; type III/IV structures were not detected. Type II-based ABH were expressed on erythrocytes of all blood groups. Group A1 and A2 erythrocytes additionally expressed type III/IV precursors, whereas group B and O erythrocytes did not. Intensity of A/B antigen expression differed among group A1 , A2 , A1 B, A2 B and B erythrocytes. On group A2 erythrocytes, type III H structures were largely un-glycosylated with the terminal "A" sugar α-GalNAc. Together, these studies define qualitative and quantitative differences in ABH antigen expression between erythrocytes and vascular tissues. These expression profiles have important implications that must be considered in clinical settings of ABO-incompatible transplantation when interpreting anti-ABO antibodies measured by hemagglutination assays with reagent erythrocytes. | Greer JM, Koerner TA, Hayakawa K, Hardy RR, Kemp JD (1993)
The 3G11+ antigen, a marker for murine CD4+ TH1 lymphocytes, is a ganglioside.
Glycobiology 3, 391-401 [PubMed:7691279]
[show Abstract]
Two monoclonal antibodies (mAbs), SM3G11 and SM6C10, can be used to discriminate between functionally distinct murine CD4+ T cell subsets. In this study we use high-performance thin-layer chromatography and immunostaining techniques to show that the 3G11 mAb reacts with two bands of a ganglioside fraction from murine spleen and thymus, and rat spleen. The 6C10 antibody shows no evidence of glycolipid reactivity. The 3G11+ bands have a mobility between those of the reference gangliosides GD1a and GD1b from human brain. The 3G11+ reactive bands were eluted in the disialyl fraction of rat spleen gangliosides using DEAE anion-exchange chromatography. Treatment of spleen gangliosides with endoglycoceramidase eliminates 3G11 antibody binding over time, indicating that the antigen contains a Glc beta 1-1'ceramide linkage, characteristic of a glycosphingolipid. Treatment of thymus or spleen gangliosides with sialidase eliminates binding of 3G11, thus indicating that the 3G11 epitope is dependent on the expression of one or more sialic acid residues. Immunostaining studies with a variety of reagents indicate that the 3G11+ gangliosides: (i) probably do not contain either the asialo-GM1 or the GM1 core structures; (ii) are not recognized by mAbs specific for the oligosaccharides of asialo-GM2, GM2, GD2 and GD3 gangliosides; and (iii) are also not recognized by antibodies or reagents that are specific for several structures representative of other major glycosphingolipid classes. Overall, these studies strongly suggest that the 3G11+ gangliosides have structures that have not been previously recognized in murine lymphoid tissue. Structures that could account for the known properties of the 3G11+ molecules are described. Finally, ways in which the selective expression of 3G11+ gangliosides might be linked to functionally distinct T-cell behaviours are discussed. |
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