Urea Transporter

Urea transporters (UTs) are transmembrane urea-selective channels expressed in multiple tissues. UT proteins, including UT-A in kidney tubule epithelia and UT-B in vasa recta microvessels, facilitate urinary concentrating function.
The UT-A gene family contains at least six isoforms, generated by alternative splicing, with the largest isoform being UT-A1. UT-A1 and UT-A3 are expressed in the kidney inner medullary collecting duct, and UT-A2 in the thin descending limb of Henle in both inner and outer medulla.
UT-B is mainly expressed in endothelial cell membrane of the renal medulla and in other tissues, including the brain, heart, pancreas, colon, bladder, bone marrow, and cochlea. UT-B is responsible for the maintenance of urea concentration, male reproductive function, blood pressure, bone metabolism, and brain astrocyte and cardiac functions. Its deficiency and dysfunction contribute to the pathogenesis of many diseases.