CHARACTERIZATION OF QUAIL INTESTINAL MUCIN AS A LIGAND FOR ENDOGENOUSQUAIL LECTIN

The S-type lectins have been shown to be components of mucosal scrapin gs, and in avian systems these lectins have been localized immunohisto chemically to the mucosal surface and goblet cells of the intestine. T he interaction of lectin specifically with purified mucin has not, how ever, been established. Quail intestinal mucin was purified by two sub sequent isopycnic density-gradient centrifugations in CsCl and chromat ography on Sepharose Cl-2B. Purified mucin, obtained from the void vol ume of the Sepharose column, was characterized by SDS/PAGE, amino acid and carbohydrate analyses, sensitivity to thiol reduction, and cross- reactivity with antibody preparations to rat and human intestinal muci ns on Western blots. Antibody raised against purified quail mucin part ially cross-reacts with purified rat, rabbit and human intestinal muci ns, and specifically labels the mucosal surface and goblet cells of qu ail intestine by the immunoperoxidase technique. Protein eluted by lac tose from an affinity matrix composed of quail intestinal mucin posses sed the same molecular mass on SDS/PAGE as intestinal lectin and react ed on Western blots with a lectin-specific antibody. The data clearly demonstrate the co-localization of lectin and mucin in the quail intes tine and also the ability of the lectin to specifically interact with the purified mucin, raising the question of the role of endogenous lec tins in secretions.