Rab 11 is an apically located small GTP-binding protein in epithelial tissues

Rab proteins are involved in many aspects of dynamic vesicle processing within eukaryotic cells. We have previously identified Rab 11 in gastric parietal cell tubulovesicle membranes. We have produced a monoclonal antibody that is specific for Eabll. In all rabbit tissues examined, Rab 11 immunoreactivity was highly enriched in epithelial cells. In the gastric fundus, parietal cells were stained in a pattern consistent with localization on tubulovesicles. Surface mucous cells of both the fundus and antrum demonstrated punctate subapical staining. Ileal and proximal colonie enterocyte labeling was observed deep to the brush borders. In the distal colon, staining was observed in the apical regions of mid-crypt cells. In skin and esophagus, punctate immunoreactivity was present in the medial layers of the squamous epithelia. Prominent Rab 11 immunoreactivity was present in hepatocytes deep to the bile canaliculi. Punctate subapical staining was observed in pancreatic acinar cells. Apical staining was also observed in collecting duct cells and in the glandular cells of the prostate. These results indicate that Rab 11 is expressed in apical vesicular populations in discrete epithelial cell populations.