IMMUNO-LOCALIZATION OF H+ PEPTIDE COTRANSPORTER IN RAT DIGESTIVE-TRACT/

In the mammalian digestive tract, small peptides are absorbed by a H+- coupled peptide transport system. Using an antibody against the rat H/peptide contransporter (PepT1), we examined the localization of PepT1 immunohistochemically along the rat digestive tract. PepT1 was detect ed in the small intestine (duodenum, jejunum, and ileum), but not in t he esophagus, stomach, colon, or rectum. PepT1 was especially enriched in the villi, where it was localized at the brush border of the absor ptive epithelial cells. PepT1 was not detected in the mucus-secreting goblet cells or less-differentiated epithelial cells in the crypts. Th ese observations show that PepT1 is specific to the brush border of th e differentiated absorptive epithelial cells and suggest that H+-coupl ed uptake of small peptides and peptide-like drugs occurs at the apica l membrane of these cells in the small intestine. (C) 1996 Academic Pr ess, Inc.