Mucin, blood group specific

Gastric mucin is the classical source of the so-called mucoitin sulfates of Levene 1) (see below). It has been an important source of the blood-group specific polysaccharides (see above), which appear to be the major known components 76), Other polysaccharide components are heparin, two chondroitin sulfates (77), and a zoopolysaccharide composed of A-ace-tyl-D-glucosamine, D-galacturonic acid, and sulfuric acid 78). 

An interesting practical application of these factors has been initiated by Morgan,127- 128 who prepared an artificial antigen with Group A specificity by combining the Blood Group A factor from hog mucin with a... 

Carbohydrate-related tumor markers either are (1) antigens on the tumor cell surface or (2) secreted by the tumor cells. Monoclonal antibodies have been developed against these antigens. These markers have been found to be clinically useful as tumor markers and tend to be more specific than naturally secreted markers, such as enzymes and hormones. Biochemically, they are high molecular weight mucins (Table 23-10) or blood group antigens (Table 23-11). 

Present knowledge on the biosynthesis of the prosthetic groups of OSM and porcine submaxillary mucin (PSM) is summarized in Fig. 12. Five glycosyltransferases are required for the synthesis of the most complex oligosaccharide side chain, the pentasaccharide present in PSM with human blood group A specificity (Carlson, 196, Section II). Four of these five enzymes are required for the synthesis of the side chain of blood group A-negative PSM two transferases are required for incorporation of the disaccharide side chain of OSM. 

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