Localization and topology of a urate transporter/channel, a galectin, in epithelium-derived cells.
Localization and topology of a urate transporter/channel, a galectin, in epithelium-derived cells.
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尿酸盐转运蛋白/通道（半乳糖凝集素）在上皮衍生细胞中的定位和拓扑。
DOI：
10.1152/ajpcell.2001.281.6.c1926
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Abramson,RG
中科院分区：
文献类型：
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作者：
Rappoport,JZ;Lipkowitz,MS;Abramson,RG
本实验室克隆的重组蛋白(UAT)在脂质双层中起尿酸转运体/通道的作用。由于UAT是一种半乳糖凝集素，是一类被认为是可溶的蛋白质家族，因此对UAT在活细胞中的定位和拓扑结构进行了评估。UAT在多种上皮源性细胞系中以质膜为靶标，在极化细胞中，UAT靶向于顶膜和基侧膜。UAT的氨基末端和羧基末端都位于细胞膜的胞质侧，而细胞表面的生物素化研究表明，UAT不仅是一种细胞膜相关蛋白，而且至少含有一个胞外结构域。MADIN-Darby犬肾细胞在功能和免疫学上都显示含有明显的UAT同源物；然而，UAT的转染并不改变尿酸盐的摄取。由于免疫共沉淀研究表明，UAT既能形成同源多聚体，也能形成异源多聚体，因此有人认为，内源性通道的单体部分地被转染后表达的蛋白质单体所取代，从而维持尿酸摄取在基础水平上的恒定。
Recombinant protein produced from a cDNA cloned in our laboratory (UAT) functions in lipid bilayers as a urate transporter/channel. Because UAT is a galectin, a family of proteins presumed to be soluble, the localization and topology of UAT were assessed in living cells. UAT was targeted to plasma membrane in multiple epithelium-derived cell lines and, in polarized cells, was targeted to both apical and basolateral membranes. The amino and carboxy termini of UAT were both detected on the cytoplasmic side of plasma membranes, whereas cell surface biotinylation studies demonstrated that UAT is not merely a cytosolic membrane-associated protein but contains at least one extracellular domain. Madin-Darby canine kidney cells were shown both functionally and immunologically to contain an apparent homolog of UAT; however, transfection with UAT did not modify urate uptake. Because coimmunoprecipitation studies revealed that UAT is capable of forming both homo- and heteromultimers, it is proposed that monomers of endogenous channels are in part replaced by monomers of the protein expressed subsequent to transfection, thereby maintaining constancy of urate uptake at basal levels.