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. Author manuscript; available in PMC: 2016 Dec 1.
Published in final edited form as: Biochim Biophys Acta. 2015 Aug 28;1856(2):211–225. doi: 10.1016/j.bbcan.2015.08.003

Figure 2. Overview of mucin type O glycosylation.

Figure 2

O-glycosylation is initiated by the activity of ppGalNAcTs, which attaches an N-acetylgalactosamine to Ser/Thr (highlighted in yellow) amino acid residues in the tandem repeat region, resulting in the formation of a Tn antigen. This Tn antigen formed can be extended by activity of C1GALT1 to form the T/Core 1 antigen. Alternatively, Tn can be modified by sialyltransferase to form sialyl Tn (sTn). The Core 1 antigen can be further elongated to form the Core 2 structure. Further, Core 2 structure is extended to several structures, including Lex, sLex, Lea, and sLea. Tn can also be extended by activity of other glycosyltransferases to form several other core structures (i.e., Cores 3 – 8).