The protein encoded by this gene belongs to the urea transporter family. In mammalian cells, urea is the chief end product of nitrogen catabolism, and plays an important role in the urinary concentration mechanism. This protein is expressed in the inner medulla of the kidney, and mediates rapid transepithelial urea transport across the inner medullary collecting duct. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Sep 2011].