Strategic biochemical analysis of mucins

MUG-type mucins comprise a family of structurally related molecules, which are expressed in epithelia of the body that are in close contact with the m ilieu. Because of their large sizes and very complex structures, containing very extensive O-glycosylation, MUG-type mucins are difficult to study by conventional techniques. Many see MUG-type mucins as protective molecules; however, functional studies on the individual MUG-type mucins are very scar ce. At present, essential steps in MUG research are to characterize the spe cific expression patterns of each MUC-type mucin in the body and to find me thods to reliably quantify these MUC-type mucins. These aims can only be me t at the level of the primary sequences of the MUG-type mucins, as the O-gl ycosylation even within one species of MUG-type mucin is not only very comp lex, but may also vary among individuals, organs, and cell types. We will d iscuss some recent advances in mucin research, particularly the identificat ion of MUC precursor molecules in metabolic labeling experiments. We will t ry to define some strategic considerations in the study of the expression p atterns of MUG-type mucins, which circumvent the complications caused by th e very complex and heterogeneous O-glycosylation of the molecules. (C) 1998 Academic Press.