Cloning of a water channel homolog expressed in brain meningeal cells and kidney collecting duct that functions as a stilbene-sensitive glycerol transporter.
Cloning of a water channel homolog expressed in brain meningeal cells and kidney collecting duct that functions as a stilbene-sensitive glycerol transporter.
复制标题
DOI：
--
复制
发表时间：
1994-08
期刊：
影响因子：
--
通讯作者：
T. Ma;A. Frigeri;H. Hasegawa;A. Verkman
中科院分区：
文献类型：
--
作者：
T. Ma;A. Frigeri;H. Hasegawa;A. Verkman
为了寻找与通道形成整合蛋白（CHIP 28）、水通道-集合管（WCH CD）和汞不敏感水通道（MIWC）具有同源性的大鼠肾基底外侧膜水转运蛋白，我们克隆了一个主要内在蛋白家族的新成员（GLIP，Glycerol Intrinsic Protein）。GLIP cDNA具有855个碱基对的开放阅读框架，编码30.5-kDa的蛋白，与水通道具有19-23%的氨基酸同一性，与细菌甘油促进剂GlpF具有36%的同一性。北方印迹分析显示，在肾脏，脑和肺中编码GLIP的5.5-淀粉酶mRNA; RT-PCR/Southern印迹分析表明，GLIP在肾脏，脑，肺，眼，结肠，胃和骨骼肌中表达，但不在心脏，肝脏和脾脏中表达。原位杂交显示GLIP mRNA在大鼠肾脏髓质集合管中有表达。免疫荧光检测显示，GLIP蛋白在肾集合管主细胞和脑膜细胞的基底外侧膜上有表达。在表达GLIP cRNA的非洲爪蟾卵母细胞中的功能测量显示，与注水的卵母细胞相比，[3 H]甘油摄取增加> 20倍;甘油摄取被二异硫氰基二磺酸二苯乙烯（0.2 mM）抑制88%，被根皮素（0.25 mM）抑制36%。GLIP不能作为水、尿素、肌醇、葡萄糖、乳酸盐和单价离子的转运蛋白。甘油摄取在卵母细胞表达CHIP 28和MIWC是没有什么不同的注水控制。GLIP代表第一个哺乳动物水通道同系物，选择性地运输水以外的溶质。GLIP的生理底物和作用仍有待阐明。
In searching for a basolateral membrane water transporter in rat kidney with homology to channel forming integral protein (CHIP28), water channel-collecting duct (WCH-CD), and mercurial-insensitive water channel (MIWC), we cloned a new member of the major intrinsic protein family (GLIP, GLycerol Intrinsic Protein). GLIP cDNA had an 855-base pair open reading frame encoding a 30.5-kDa protein with 19-23% amino acid identity to the water channels and 36% identity to the bacterial glycerol facilitator GlpF. Northern blot analysis showed a 5.5-kilobase mRNA encoding GLIP in kidney, brain, and lung; RT-PCR/Southern blot analysis indicated expression of GLIP in kidney, brain, lung, eye, colon, stomach, and skeletal muscle, but not in heart, liver, and spleen. In situ hybridization in rat kidney showed GLIP mRNA expression in medullary collecting duct. Immunofluorescence with a peptide-derived polyclonal antibody showed GLIP protein expression in basolateral membrane of kidney collecting duct principal cells and brain meningeal cells. Functional measurements in Xenopus oocytes expressing GLIP cRNA showed a > 20-fold increase in [3H]glycerol uptake compared with water-injected oocytes; glycerol uptake was inhibited 88% by diisothiocyanodisulfonic stilbene (0.2 mM) and 36% by phloretin (0.25 mM). GLIP did not function as a transporter for water, urea, inositol, glucose, lactate, and monovalent ions. Glycerol uptake in oocytes expressing CHIP28 and MIWC was not different from that in water-injected controls. GLIP represents the first mammalian water channel homolog that selectively transports a solute other than water. The physiological substrate(s) and role(s) of GLIP remain to be elucidated.