A novel mutation at the JK locus causing Jk null phenotype in a Chinese family.
Urea transporters are a group of proteins that facilitate urea movement across biological membranes. Kidd blood group (Jk antigen) and urea transporter of human erythrocytes are carried by the same protein UT-B. To investigate the molecular basis of the Jk null phenotype in the Chinese population, blood samples from Chinese individuals were screened using the 2 mol/L urea solution hemolysis test. Urea and water permeability of erythrocytes membrane was measured by stopped-flow light scattering. Genomic DNA was extracted from lymphocytes. UT-B gene of JKnnu's family was analyzed using genomic PCR by primers designed to cover sequences of all exons and exon-intron boundaries in human UT-B gene. One Jk null subject was found from twenty thousand screened Chinese individuals, and it was confirmed that this individual did not express the erythrocyte urea transporter. Genomic sequence analysis of the Jk null individual showed that there were two point mutations, G-->C, which is novel, and G-->A, at the 3'-acceptor splice site (AG) of intron 5 of UT-B gene. Exon 6 is spliced out in the UT-B transcript due to either of these mutations. Water permeability in Jk null erythrocytes (Pf, -0.00037 cm/s) was significantly lower than that in normal erythrocytes (Pf, -0.00062 cm/s) after HgCl2 incubation, providing evidence for UT-B facilitated water transport in human erythrocytes.
Department of Pathophysiology, School of Medical Science, Jilin University, Changchun 130021, China.
Yan
Y
Meng
Xueyan
X
Zhou
Yang
Y
Li
Dan
D
Zhao
Shuyuan
S
Liang
Xuejian
X
Zhao
Baoxue
B
Yang
D044466:Asian People / Q000235:genetics*; D002463:Cell Membrane Permeability / Q000235:genetics; D002681:China; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D005260:Female; D005838:Genotype; D006801:Humans; D007667:Kidd Blood-Group System / Q000235:genetics*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D012965:Sodium Chloride / Q000494:pharmacology; D014508:Urea / Q000378:metabolism / Q000494:pharmacology; D000096982:Urea Transporters
D007667:Kidd Blood-Group System; D026901:Membrane Transport Proteins; D012965:Sodium Chloride; D014508:Urea; D000096982:Urea Transporters