Purification and characterization of sialyl-Le(a)-carrying mucins of human bile; evidence for the presence of MUC1 and MUC3 apoproteins.

摘要: Purification of sialyl-Le(a)-carrying mucins from primary human bile by trichloroacetic acid precipitation, delipidation, and gel filtration in guanidinium chloride gave three separable fractions, one which was further purified affinity chromatography. These named SBG1 (for soluble glycoprotein), SBG2, SBG3 had molecular masses > 1100, 800-950, 100-250 kDa, respectively, as estimated sodium dodecyl sulfate-polyacrylamide electrophoresis. Their mucin characteristics were indicated a high carbohydrate content, ranging 74 to 95%. The compositions the presence very long fucosylated polylactosamine chains. Amino analyses showed abundance serine threonine all fractions (19-36%), confirming their mucin-like nature. Immunochemical deglycosylated samples detected MUC1 apoprotein SBG2 MUC3 protein SBG1. To our knowledge, this is first report being purified. This no significant reduction size upon trypsin treatment or disulfide bond alkylation. Gel secondary that distribution glycoproteins similar found bile, immunochemical analysis present samples. In sample an additional fraction isolated, insoluble 6 M chloride, but solubilized mRNAs gallbladder epithelia analyzed Northern blot hybridizations showing not MUC2 genes expressed.