As well as being a Golgi membrane resident, the histo-blood group ABO system transferase (ABO) can be proteolytically processed by an unknown protease into a soluble form, fucosylglycoprotein alpha-N-acetylgalactosaminyltransferase (sABO). A, B and AB individuals express glycosyltransferase activities that convert the H antigen to the A antigen (by addition of GalNAc), to the B antigen (by addition of Gal) or to the AB antigen (by the addition of both GalNAc and Gal). O group individuals lack such activity. Differences in four critical amino acids (176, 235, 266 and 268) alter the specificity from an A to a B glycosyltransferase (Yamamoto et al. 1990, Yamamoto & McNeill 1996, Seto et al. 1999, Alfaro et al. 2008). The soluble form of histo-blood group A transferase (sABO-A) utilises UDP-GalNAc to transfer N-acetylgalactosamine (GalNAc) to the H antigen formed via Type 1 chains to form the A antigen in secretors (A antigen-sec) (Patenaude et al. 2002, Persson et al. 2007).
Alfaro, JA, Zheng, RB, Persson, M, Letts, JA, Polakowski, R, Bai, Y, Borisova, SN, Seto, NO, Lowary, TL, Palcic, MM, Evans, SV
Yamamoto, F, Clausen, H, White, T, Marken, J, Hakomori, S
Yamamoto, F, McNeill, PD
Patenaude, SI, Seto, NO, Borisova, SN, Szpacenko, A, Marcus, SL, Palcic, MM, Evans, SV
Seto, NO, Compston, CA, Evans, SV, Bundle, DR, Narang, SA, Palcic, MM
Persson, M, Letts, JA, Hosseini-Maaf, B, Borisova, SN, Palcic, MM, Evans, SV, Olsson, ML
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