1.A.28.1.3
Kidney urea transporter, UT-A1, of 414aas and 11 TMSs in a 5 + 5 + 1 TMS arrangement. It mediates transepithelial urea transport in the inner medullary collecting duct for urinary concentration. Interacts with the C-terminus of Snapin (O95295) and SNARE-associated protein) (Mistry et al., 2007). Also transports formamide, acetamide, methylurea, methylformamide, ammonium carbamate, and acrylamide, and possibly dimethylurea and thiourea as well (Zhao et al., 2007). Mutation of the N-linked glycosylation sites reduces urea flux by reducing the UT-A1 half-life and decreasing its accumulation in the apical plasma membrane. The related erythrocyte urea transporter, UTB (UT-B; TC# 1.A.28.1.5) has been reviewed (Bagnasco, 2006). Mutation of the N-linked glycosylation sites reduces urea flux by reducing the UT-A1 half-life and decreasing its accumulation in the apical plasma membrane (Chen et al. 2006). In vivo, inner medullary collecting duct cells may thus regulate urea uptake by altering UT-A1 glycosylation in response to AVP stimulation.