Epithelial mucins and bacterial adhesion - Carbohydrate Chemistry: Chemical and Biological Approaches - page 600

SLe a

α -Fuc p -(1 4)

α -Neu p 5Ac-(2 3)- β -Gal p -(1 3)- β -Glc p NAc

α 4-Fuc-T

α -Neu p 5Ac-(2 3)- β -Gal p -(1 3)- β -Glc p NAc

ST3Gal III

β -Gal p -(1 3)- β -Glc p NAc

α 2-Fuc-T

H type 1

α -Fuc p -(1 2)- β -Gal p -(1 3)- β -Glc p NAc

α 4-Fuc-T α 3-Gal-T α 3-GalNAc-T

α -Fuc p -(1 4) α -Gal p -(1 3)

β

α -Gal pNAc -(1 3)

β

-Gal p -(1 3)- -Glc p NAc -Gal p -(1 3)-

β

-Glc p NAc -Gal p -(1 3)- -Glc p NAc

β β β

-Fuc p -(1 2) -Fuc p -(1 2) -Fuc p -(1 2)

α α α

Le b B type 1 A type 1

β -Gal pNAc -(1 4)

α -Fuc p -(1 3)

SLe x Sda

α -Neu p 5Ac-(2 3)- β -Gal p -(1 4)- β -Glc p NAc α -Neu p 5Ac-(2 3)- β -Gal p -(1 4)- β -Glc p NAc

α 3-Fuc-T β 4-GalNAc-T2

α -Neu p 5Ac-(2 3)- β -Gal p -(1 4)- β -Glc p NAc

ST3Gal IV & VI

β -Gal p -(1 4)- β -Glc p NAc

α 2-Fuc-T

H type 2

-Fuc p -(1 2)- -Gal p -(1 4)- -Glc p NAc

α β β

α 3-Fuc-T α 3-Gal-T α 3-GalNAc-T

α -Fuc p -(1 3) α -Gal p -(1 3) α -Gal pNAc -(1 3)

β -Gal p -(1 3)- β -Glc p NAc β -Gal p -(1 4)- β -Glc p NAc β -Gal p -(1 4)- β -Glc p NAc

α -Fuc p -(1 2) α -Fuc p -(1 2) α -Fuc p -(1 2)

Le y B type 2 A type 2

Fig. 2 Biosynthesis of type-1 and type-2 H, A, and B, antigens and Lewis group de-
terminants on type-1 and type-2 chains on mucin type O-glycans. a 1,2-fucosyl-
transferases ( a 2-Fuc-T) catalyze the transfer of a Fucp residue in a 1,2-linkage on terminal
Galp residue of type 1: b -Galp-(1 - 3)- b -GlcpNAc or type 2: b -Galp-(1 - 4)- b -GlcpNAc
disaccharides forming the H type 1 or H type 2 antigens, which are precursors of the A and
B type 1 or 2 blood group antigens, and of Le b or Le y antigens, respectively. Type 1 and 2
disaccharides can also be sialylated by an a 2,3-sialyltransferase and further fucosylated by
one of the a 1,3/4-fucosyltransferases, generating the sLe a or sLe x structures, respectively.
Sialylated type 2 disaccharide is also a substrate for b 4-GalNAcT-II, resulting in the
synthesis of the Sd a antigen.

structure, called the Thomsen-nouvelle (Tn) antigen. 20 homologous
human ppGalNAc-T genes (GALNT) have been characterized (Table 2). 8
ppGalNAc-T isoforms display cell- and tissue-specific expression patterns