1. No category

Histo (blood) group A2 phenotype and anti-A1 reactive IgM
arising in the same enzymatic process
O
O-GalNAc T A2
A2
O-GalNAc T A1
s o m a t i c g l y c oO-GalNAc
s y l a t i o n T A2
O-GalNAc T A
2
O-GalNAc
T A2
Polyreactive ancestral IgM
Linkage sites
(H)
Polyreactive ancestral IgM
Anti-A1 reactive
Anti-A2 reactive
A1
domain
domain
Anti-A = Anti-A1 + Anti-A2
Somatic glycosylation
Anti-A1
Isolation
Anti-A1
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Developmental isolation of the ancestral anti-A1 reactivity within the blood group A2 by
exclusive encoding of a somatic, O-GalNAc transferase A2, genetically distinct from the
A1 transferase (Yamamoto et al., 1992; Hakomori, 1999; Svensson et al., 2009) and
providing the A2 epitope generation on red cells and mucoepithelial cells, moreover,
suggesting simultaneous glycosylation of the ancestral anti-A2 domain within the nonsomatically encoded, non-immune, polyreactive IgM molecule and blocking the appearance of an anti-A2 reactivity in the circulation. Arend, Peter (2014): Histo (blood) group O
“inbreeding” as it relates to A-allelic functions and ancestral IgM formation; a hypothesis*. figshare.
http://dx.doi.org/10.6084/m9.figshare.1018769; Hakomori, S., 1999. Biochim. Biophys. Acta 1473,
247-266; Antigen structure and genetic basis of histo-blood groups A, Svensson, L.; Rydberg, L.; de
Mattos, L. and Henry, S. 2009. Blood group A1 and A2 revisited: an immunochemical analysis. Vox
sanguinis 96, 1 56-6, DOI: 10.1111/j. 1423-0410.2008.01112.x B and O: their changes associated
with human cancer; Yamamoto, F.; McNeill, PD. and Hakomori, S. 1992: Human histo-blood group
A2 transferase coded by A2 allele, one of the A subtypes, is characterized by a single base deletion in
the coding sequence, which results in an additional domain at the carboxyl terminal. Biochem Biophys
Res Commun, 187:366-374.