Urea transporter

An urea transporter is a membrane transport protein, transporting urea.

Urea Transporter A1
Urea transporter 1 transports urea across the apical membrane into the intracellular space of luminal cells in the inner medullary collecting duct of the kidneys. UT-1 is activated by ADH, but is a passive transporter. It reabsorbs up to 40% of the original filtered load of urea.

Urea Transporter A2
Urea Transporter 2 transports urea across the apical membrane into the luminal space of cells in the thin descending loop of Henle of the kidneys.

Urea Transporter A3
Urea transporter 3 transports urea into the interstitium of the Inner Medullary Collecting Duct.

Urea Transporter A4
Urea transporter 4 has been detected in rat but not mouse kidney medulla.

Urea Transporter A5
Urea transporter 5 is not expressed in the kidney but in the testis.

Urea Transporter B
UT-B is expressed in the basolateral and apical regions of the descending Vasa recta.