Cellular localization of intestinal calcium-binding protein in pig duodenum.

The gamma-globulin fraction of a rabbit antiserum against porcine intestinal calcium-binding protein (CaBP) was used in an immunoperoxidase method to study CaBP localization in porcine duodenal tissue. Specific immunostaining, indicative of the presence of CaBP, was noted within the cytoplasm of the duodenal epithelial cells. No CaBP was detected in goblet cells or in the subepithelial layers. When the specific antibody was replaced by either nonimmune rabbit gamma-globulin or when the specific antibody was preadsorbed with excess CaBP, no positive immunostaining was seen. Our studies lend support to the hypothesis that CaBP may function in intracellular calcium transport.