The mucins are a family of large glycoproteins characterized by abundant O-glycans clustered in long mucin domains. These domains are extended stiff rods with the glycans pointing in all directions. This cluster of glycans makes the central protein core inaccessible to proteases and generates a glycan surface of clustered antigens. There are two main groups of mucins; the classical gel-forming polymeric mucins (MUC2, MUC5AC, MUC5B, and MUC6) and a more heterogeneous group of monomeric transmembrane mucins (MUC1, MUC3, MUC4, MUC12, MUC13, MUC15, MUC16, MUC17, MUC20, and MUC21). A majority of the mucins are found at the mucosal surfaces of the body where they build the protective mucus and the epithelial cell glycocalyx. Other mucins, for example, MUC1, have wider distribution to many cells of the body including classical immune cells.
Keywords: Cancer antigen; Dendritic cell; Gel-forming; Glycoprotein; Glycosylation; Goblet cell; Intestine; Mammary gland; Mucin; Mucus; O-glycan; Pancreas; Respiratory tract; SEA; Tumor marker; VWD