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.