Differential cellular expression of three types of inositol 1,4,5-trisphosphate receptor in rat gastrointestinal epithelium

In epithelial tissues of rat gastrointestinal tract, inositol 1,4,5-trisphosphate receptor type-1, type-2 and type-3 were immunolocalized with type-specific monoclonal antibodies (KM1112, KM1083 and KM1082, respectively). The immunoreactivities for inositol 1,4,5-trisphosphate receptor type-1 and type-3 were localized predominantly in gastric parietal cells, whereas no immunoreactivity was observed in gastric chief cells. Inositol 1,4,5-trisphosphate receptor type-2 was immunolocalized exclusively in goblet cells of small intestine, especially of duodenum, but not in goblet cells of colon. Western blotting analysis verified 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 secretory functions.