The gene encoding the urea transporter of human erythrocytes (HUT11 clone) has been cloned recently (Olives, B., Neau, P., Bailly, P., Hediger, M. A., Rousselet, G., Cartron, J. P., and Ripoche, P. (1994) J. Biol. Chem. 269, 31649-31652). Now, this gene has been assigned to chromosome 18q12-q21 by in situ hybridization, as also found for the Kidd (Jk) blood group locus. In coupled transcription-translation assays, the HUT11 cDNA directed the synthesis of a 36-kDa protein which was immunoprecipitated by a human anti-Jk3 antibody produced by immunized Jk(a-b-) donors whose red cells lack Kidd antigens. The anti-Jk3 antibody also immunoprecipitated a protein material of 46-60 kDa from all red cell membranes, except those from Jk(a-b-) cells. After N-glycanase digestion the 46-60-kDa component was reduced to 36 kDa. A rabbit antibody raised against the predicted NH2-terminal amino-acids of the HUT11 protein reacted on immunoblots with a 46-60-kDa component present in all human erythrocytes except those from Jk(a-b-) individuals. Jk(a-b-) red cells lack the Kidd/urea transport protein and have a selective defect of the urea transport capacity, but a normal water permeability and aquaporin-associated Colton blood group antigens. These findings indicate that the erythrocyte urea transporter is encoded by the Kidd locus and may have implications for the biology of urea transporters and their tissue-specific regulation.

The red cell ICAM-4/LW blood group glycoprotein, which belongs to the family of intercellular adhesion molecules (ICAMs), has been reported to interact with CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1) ␤ 2 integrins. To better define the basis of the ICAM-4/␤ 2 integrin interaction, we have generated wild-type, domain-

ICAM-4 (LW blood group glycoprotein) is an erythroid-specific membrane component that belongs to the family of intercellular adhesion molecules and interactsThe main physiological function of red blood cells (RBCs), 1 which encapsulate hemoglobin, is to ensure the respiratory gases transport throughout the human body. However, the recent demonstration that mature RBCs express a growing number of adhesion molecules, many of which exhibit blood group specificities (1-3), reinforces the necessity to revisit the functional interaction of RBCs with leukocytes, platelets, and vascular endothelium under normal and pathological conditions.It is interesting that many RBC adhesion molecules contain protein domains characteristic of the immunoglobulin superfamily, suggesting some recognition function. These molecules might participate in the normal RBC physiology by playing a role during erythropoiesis (differentiation, maturation, enucleation, release), self-recognition mechanisms, red cell turnover, and cell aging through cellular interactions with counter

No abstract