At physiological expression levels the Kidd blood group/urea transporter protein is not a water channel.

The Kidd (JK) blood group locus encodes a urea transporter that is expressed on human red cells and on endothelial cells of the vasa recta in the kidney. Here, we report the identification in human erythroblasts of a novel cDNA, designated HUT11A, which encodes a protein identical to the previously reported erythroid HUT11 urea transporter, except for a Lys(44) --> Glu substitution and a Val-Gly dipeptide deletion after proline 227, which leads to a polypeptide of 389 residues versus 391 in HUT11. Genomic typing by polymerase chain reaction and transcript analysis by ribonuclease protection assay demonstrated that HUT11A encodes the true Kidd blood group/urea transporter protein, which carries only 2 Val-Gly motifs.

Characterization of the gene encoding the human Kidd blood group/urea transporter protein. Evidence for splice site mutations in Jknull individuals.

The Kidd (JK) blood group is carried by an integral membrane glycoprotein which transports urea through the red cell membrane and is also present on endothelial cells of the vasa recta in the kidney. The exon-intron structure of the human blood group Kidd/urea transporter gene has been determined. It is organized into 11 exons distributed over 30 kilobase pairs.

The molecular basis of the Kidd blood group polymorphism and its lack of association with type 1 diabetes susceptibility.

The Kidd blood group locus encodes a urea transporter which is expressed on human red cells and in the kidney. This gene is located on chromosome 18q12, and evidence for linkage and association with type 1 diabetes mellitus has been reported. To investigate this further, the genetic basis for the blood group Jk(a)/Jk(b) polymorphism was first determined by sequencing reverse-transcribed reticulocyte RNAs from Jk(a+b-) and Jk(a-b+) donors.

Endothelial cells of the kidney vasa recta express the urea transporter HUT11.

The cell specific expression of the human urea transporter HUT11 in human and rat kidneys was investigated by immunochemistry and in situ hybridization. Using specific rabbit polyclonal antibodies directed against the N-terminal part and the C-terminal part of HUT11, we found that endothelial cells of medullary vasa recta (outer and inner medulla) express HUT11. In addition, an HUT11-related protein expressed by smooth muscle cells of cortical arterioles can be detected by the anti-HUT11 N-terminal peptide antibody but not the anti-HUT11 C-terminal peptide antibody.

Functional differentiation of the human red blood cell and kidney urea transporters.

The recent cloning of two urea transporters will allow to better understand their role in the urinary concentrating mechanism. This physiological approach needs to be sustained by a knowledge of their functional characteristics. We compared the pharmacological properties of the human red blood cell and kidney urea transporters (HUT11 and HUT2) in the Xenopus oocyte expression system.