DIFFERENTIAL CELLULAR EXPRESSION OF 3 TYPES OF INOSITOL 1,4,5-TRISPHOSPHATE RECEPTOR IN RAT GASTROINTESTINAL EPITHELIUM

In epithelial tissues of rat gastrointestinal tract, inositol 1,4,5-tr isphosphate receptor type-1, type-2 and type-3 were immunolocalized wi th type-specific monoclonal antibodies (KM1112, KM1083 and KM1082, res pectively). The immunoreactivities for inositol 1,4,5-trisphosphate re ceptor type-1 and type-3 were localized predominantly in gastric parie tal cells, whereas no immunoreactivity was observed in gastric chief c ells. Inositol 1,4,5-trisphosphate receptor type-2 was immunolocalized exclusively in goblet cells of small intestine, especially of duodenu m, but not in goblet cells of colon. Western blotting analysis verifie d the immunolocalizations of the inositol 1,4,5-trisphosphate receptor types in these tissues. The differential expression of the inositol 1 ,4,5-trisphosphate receptor types may be responsible for various gut s ecretory functions.