MOLECULAR-CLONING AND EXPRESSION OF A MEMBER OF THE AQUAPORIN FAMILY WITH PERMEABILITY TO GLYCEROL AND UREA IN ADDITION TO WATER EXPRESSED AT THE BASOLATERAL MEMBRANE OF KIDNEY COLLECTING DUCT CELLS
MOLECULAR-CLONING AND EXPRESSION OF A MEMBER OF THE AQUAPORIN FAMILY WITH PERMEABILITY TO GLYCEROL AND UREA IN ADDITION TO WATER EXPRESSED AT THE BASOLATERAL MEMBRANE OF KIDNEY COLLECTING DUCT CELLS
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DOI：
10.1073/pnas.91.14.6269
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发表时间：
1994-07-05
影响因子：
11.1
通讯作者：
MARUMO, F
中科院分区：
文献类型：
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作者：
ISHIBASHI, K;SASAKI, S;MARUMO, F
水在高透水性膜中的传输是通过水选择性孔即水通道进行的。最近克隆的水通道揭示了这些蛋白质的水选择性的特点时，表达在非洲爪蟾卵母细胞或脂质体重组。目前，假定水道的功能仅是输送水。我们现在报告克隆的成员的水通道，也运输非离子小分子，如尿素和甘油。我们将这种通道命名为水通道蛋白3（AQP 3），因为它具有显著的透水性。AQP 3与主要内在蛋白（MIP）家族蛋白质具有氨基酸序列同一性，所述主要内在蛋白（MIP）家族蛋白质包括AQP-通道形成整合膜蛋白、AQP-集合管、MIP、AQP-γ液泡膜内在蛋白、微管蛋白26和甘油促进剂（33-42%）。因此，AQP 3是MIP家族的额外成员。通过视频显微镜测量的非洲爪蟾卵母细胞的渗透水渗透性在注射AQP 3转录本的卵母细胞中比注射水的卵母细胞高10倍。渗透水渗透性的增加被抑制氯化汞，这种效果被逆转的还原剂，2-巯基乙醇。虽然在较小的程度上，AQP 3也促进了非离子小溶质，如尿素和甘油的运输，而以前克隆的水通道是可渗透的只有水在非洲爪蟾卵母细胞中表达时。AQP 3 mRNA在肾髓质和结肠中表达丰富。在肾脏中，它仅免疫定位于集合管细胞的基底外侧膜。AQP 3可能在集合管细胞中作为水和尿素排出机制发挥抗利尿作用。
Water transport in highly water-permeable membranes is conducted by water-selective pores-namely, water channels. The recent cloning of water channels revealed the water-selective characteristics of these proteins when expressed in Xenopus oocytes or reconstituted in liposomes. Currently, it is assumed that the function of water channels is to transport only water. We now report the cloning of a member of the water channel that also transports nonionic small molecules such as urea and glycerol. We named this channel aquaporin 3 (AQP3) for its predominant water permeability. AQP3 has amino acid sequence identity with major intrinsic protein (MIP) family proteins including AQP-channel-forming integral membrane protein, AQP-collecting duct, MIP, AQP-gamma tonoplast intrinsic protein, nodulin 26, and glycerol facilitator (33-42%). Thus, AQP3 is an additional member of the MIP family. Osmotic water permeability of Xenopus oocytes measured by videomicroscopy was 10-fold higher in oocytes injected with AQP3 transcript than with water-injected oocytes. The increase in osmotic water permeability was inhibited by HgCl2, and this effect was reversed by a reducing agent, 2-mercaptoethanol. Although to a smaller degree, AQP3 also facilitated the transport of nonionic small solutes such as urea and glycerol, while the previously cloned water channels are permeable only to water when expressed in Xenopus oocytes. AQP3 mRNA was expressed abundantly in kidney medulla and colon. In kidney, it was exclusively immunolocalized at the basolateral membrane of collecting duct cells. AQP3 may function as a water and urea exit mechanism in antidiuresis in collecting duct cells.