The multiple trans-species, genetically as-yet-undefined functions of%0A"A-like" O-GalNAc-Ser/Thr glycosylations1-3, which dominate the early%0Acarbohydrate metabolism of vertebrates, are different from the%0Aspecies-intrinsic and human phenotype-determining A-allelic enzyme proteins and/or%0Afunctions being expressed only after formation of the zygote. The volatilely%0Aexpressed "A-like" O-GalNAc glycans are structurally related to and%0Alikely imply metabolic relationships with the mucin-type

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... monosaccharide%0AGalNAcα1-O-Ser/Thr, also referred to as the Tn antigen, whose%0Aaccumulation in non-developmental tissues is a marker of malignancy, and which%0Ais thus called an "aberrant" glycosylated molecule. Historically, the "A-like"%0ATn antigen or "T nouvelle" was named upon its discovery reported in 19574 to emphasize its distinction%0Afrom the functionally similar T (Thomsen-Friedenreich) antigen, reported in%0A19305. Early O-glycan expressions, which may be observed during germ cell%0Adevelopment and embryonic stem cell differentiations, are characterized by%0Aextremely short half-lives6,7, and their enzyme%0Adepletions most likely cause the release of characteristic O-glycan-depleted,%0Acomplementary proteins, such as secretory IgM that is not restricted to B cells%0Aand might reveal the structure of the volatilely expressed, "lost" O-glycans%0Athrough germline-specific serine residues. This non-immune anti A-reactive IgM is%0Adisctinct from the innate anti-B; it has not undergone clonal selection and must%0Abe differentiated from innumerable, adaptive anti-A/B cross-specificities. Indeed,%0Athe cryptic "A-like" and/or aberrant structures may be detected by "natural"%0Aanti A and/or anti-T antibodies that are among the anti-glycan moieties present%0Ain plasma of animals including humans8, in whom the levels of anti-T%0Aantibodies are highly dependent on the ABO(H) blood group and pr [...]