Roudier Nathalie, Ripoche Pierre, Gane Pierre, Le Pennec Pierre Yves, Daniels Geoff, Cartron Jean-Pierre, Bailly Pascal
INSERM U76, Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015 Paris, France.
J Biol Chem. 2002 Nov 29;277(48):45854-9. doi: 10.1074/jbc.M208999200. Epub 2002 Sep 17.
AQP3 is a water and glycerol channel present on human erythrocytes and in various tissues. By protein and molecular biology analysis, two unrelated probands who developed alloantibodies to the high frequency antigen GIL were found to be AQP3-deficient. The defect is caused by homozygous mutation affecting the 5' donor splice site of intron 5 of the AQP3 gene. This mutation causes the skipping of exon 5 and generates a frameshift and premature stop codon. Functional studies by 90 degrees light scattering using a stopped-flow spectrometer revealed the absence of facilitated glycerol transport across red cell membranes from the probands, but the water and urea transports were normal. Expression studies into COS-7 cells followed by flow cytometry analysis showed that only cells transfected with AQP3 cDNA strongly reacted with anti-GIL antibodies. These findings represent the first reported cases of AQP3 deficiency in humans and provide the molecular basis of a new blood group system, GIL, encoded by the AQP3 protein.
水通道蛋白3（AQP3）是一种存在于人体红细胞和多种组织中的水和甘油通道。通过蛋白质和分子生物学分析，发现两名对高频抗原GIL产生同种抗体的无关先证者缺乏AQP3。该缺陷是由影响AQP3基因第5内含子5'供体剪接位点的纯合突变引起的。这种突变导致外显子5跳跃，并产生移码和过早的终止密码子。使用停流光谱仪通过90度光散射进行的功能研究表明，先证者的红细胞膜上不存在促进甘油转运的情况，但水和尿素转运正常。对COS-7细胞进行表达研究，随后进行流式细胞术分析，结果显示只有转染了AQP3 cDNA的细胞与抗GIL抗体发生强烈反应。这些发现代表了人类中首次报道的AQP3缺乏病例，并为一种由AQP3蛋白编码的新血型系统GIL提供了分子基础。
