Ko S B, Uchida S, Naruse S, Kuwahara M, Ishibashi K, Marumo F, Hayakawa T, Sasaki S
International Medicine II, Nagoya University School of Medicine, Japan.
Biochem Mol Biol Int. 1999 Feb;47(2):309-18. doi: 10.1080/15216549900201333.
A new aquaporin was isolated from rat liver based on homology to known aquaporins. A 1408 bp cDNA was sequenced (designated rAQP9L) with a 885 bp open reading frame encoding a 295 amino acid hydrophobic protein. rAQP9L has the greatest amino-acid sequence identity with human AQP9 (75%) and a less homology with AQP3 (49%) and AQP7 (47%). Northern blot analysis indicated a 1.4-kb transcript expressed strongly in liver > testis > brain = lung. Expression of rAQP9L cRNA in Xenopus oocytes increased osmotic water permeability by 6-folds which was inhibited by 0.3 mM mercury chloride by 42%. rAQP9L also facilitated glycerol and urea transport by 2- and 5-folds, respectively. The large discrepancy of tissue distribution between hAQP9 and rAQP9L suggest that rAQP9L is a new aquaporin, which is involved in transport of urea as well as water in liver.
基于与已知水通道蛋白的同源性，从大鼠肝脏中分离出一种新的水通道蛋白。对一个1408 bp的cDNA进行了测序（命名为rAQP9L），其开放阅读框为885 bp，编码一个295个氨基酸的疏水蛋白。rAQP9L与人类AQP9的氨基酸序列一致性最高（75%），与AQP3（49%）和AQP7（47%）的同源性较低。Northern印迹分析表明，一个1.4 kb的转录本在肝脏中表达强烈，其次是睾丸、脑和肺。rAQP9L的cRNA在非洲爪蟾卵母细胞中的表达使渗透水通透性增加了6倍，0.3 mM氯化汞可使其降低42%。rAQP9L还分别使甘油和尿素的转运增加了2倍和5倍。hAQP9和rAQP9L在组织分布上的巨大差异表明，rAQP9L是一种新的水通道蛋白，它参与肝脏中尿素和水的转运。
