Downregulated in adenoma (DRA) is a transmembrane glycoprotein that transports chloride ions across the cell membrane in exchange for bicarbonate ions. Expression is primarily within intestinal epithelia of ileum and colon, where DRA localizes to the apical membrane of colonocytes and some goblet cells. DRA is critical to chloride absorption, and mutations in the gene (SLC26A3) have been associated with congenital chloride diarrhea. 

Antibody characterization and validation:
This monoclonal antibody recognizes an epitope mapping between amino acids 733-761 at the C-terminus of human DRA (SLC26A3). For validation, formalin-fixed, paraffin-embedded tissues were stained. Reactivity was detected at the apical surface of villus epithelium within the ileum, but not the jejunum, where DRA is known to be absent. DRA was also detected in human colon.

Immunostaining procedure conditions: 
Antigen retrieval with Target Retrieval Solution, pH6 (Agilent Technologies, Cat. #S2367) for 15 minutes at 95°C.
Primary and secondary incubations performed using the following reagents: