Cryptic A-Like Receptor Sites in Human Erythrocyte Glycoproteins: Proposed Nature of Tn-Antigen

Abstract

Periodate oxidation and Smith degradation of desialized human erythrocyte glycoproteins lead to an almost complete destruction of galactose and some loss of galactosamine and glucosamine. Neutral sugar and hexosamine content of native MN substances are only slightly influenced by periodate oxidation. Destruction of galactose is accompanied by an uncovering of A-like receptor sites detectable by agglutinins from plants and snails, which are directed against terminal N-acetylgalactosamine. From the specificity of these antibody-like substances, it is deduced that the amino sugar functioning as receptor is α-glycosidically linked. Destruction of the receptor sites by subsequent alkaline borohydride treatment suggests that the N-acetylgalactosamine is unmasked by degradation of the alkali-labile tetrasaccharide of human erythrocyte glycoproteins. Periodate-oxidized and Smith-degraded NANA-free erythrocyte and ovarian cyst glycoproteins treated by acetolysis are potent inhibitors of anti-Tn from man, animals, and plants, suggesting that Tn-antigen is represented by terminal, α-glycosidic, peptide-bound N-acetylgalactosamine. It is concluded that Tn-antigen is probably a cryptic determinant of the alkali-labile tetrasaccharide, which has been isolated from human erythrocyte glycopeptides.

Differential expression profiles of glycosphingolipids in human breast cancer stem cells vs. cancer non-stem cells

“…In addition to GSLs indicated to be associated with CSCs in this study, the following were found to be highly expressed in human cancer but either absent or present in negligible amounts in normal cells/tissues: (i) blood group A-like antigens expressed in tumor cells of blood group O or B patients [the structure is GalNAcα1-O-Ser/Thr, termed Tn (63)(64)(65); (ii) sialyl 2-6Tn antigen [i.e., NeuAcα2-6GalNAcα1-O-Ser/Thr (66)]; and (iii) extended type-I antigen [i.e., Le a on Le a (67) or Le b on Le a (68,69)]. Whether these glycan structures are somehow associated with CSCs is an interesting point for future studies.…”

Secretion-associated lectin-binding sites as a parameter of hormone dependence in mammary carcinoma

“…(Uhlenbruck et al, 1969) and N-acetyl-Dgalactosamine (Dahr et al, 1974) respectively, were used. The histochemical studies were performed on formaldehydefixed tissue sections from 75 patients, as previously described (Klein et al, 1978(Klein et al, , 1979.…”

Expression of the Tn antigen on erythroid cells from a patient with Tn syndrome

“…Tn-positive cells were initially detected on day 3 of the second phase, and increased during erythroid maturation. Serological and biochemical evidence has shown that N-acetyl-D-galactosamine, when covalently bound to erythrocyte surface sialoglycoproteins, glycophorin A and glycophorin B by an alkali-labile O glycosidic linkage, is the chief structural determinant of Tn specificity (Dahr et al, 1974;Vainchenker et al, 1982;Springer and Desai, 1985). Previously we have demonstrated the expression of glycophorin A in erythroid cells on day 3 of the second phase using the liquid culture system (Wada et al, 1990).…”

“…This disorder may be associated with a mild hemolytic anemia, leukopenia, or thrombocytopenia, but has also been described in some acute leukemias or myeloproliferative diseases (Bird et al, 1976;Baldwin et al, 1979;Ness et aI., 1979;Vainchenker et al, 1985). The biochemical basis of Tn activation is now well characterized and corresponds to the exposure of an N-acetylgalactosamine residue carried by cell surface glycoproteins, which arises from a selective loss of a 3-/~-D-galactosyltransferase activity in Tn-positive cells (Dahr et al, 1974;Cartron et al, 1978aCartron et al, , 1978bCartron et al, , 1979.…”