Gamba G, Saltzberg S N, Lombardi M, Miyanoshita A, Lytton J, Hediger M A, Brenner B M, Hebert S C
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):2749-53. doi: 10.1073/pnas.90.7.2749.
Electroneutral Na+:Cl- cotransport systems are involved in a number of important physiological processes including salt absorption and secretion by epithelia and cell volume regulation. One group of Na+:Cl- cotransporters is specifically inhibited by the benzothiadiazine (thiazide) class of diuretic agents and can be distinguished from Na+:K+:2Cl- cotransporters based on a lack of K+ requirement and insensitivity to sulfamoylbenzoic acid diruetics like bumetanide. We report here the isolation of a cDNA encoding a thiazide-sensitive, electroneutral sodium-chloride cotransporter from the winter flounder urinary bladder using an expression cloning strategy. The pharmacological and kinetic characteristics of the cloned cotransporter are consistent with the properties of native thiazide-sensitive sodium-chloride cotransporters in teleost urinary bladder and mammalian renal distal tubule epithelia. The nucleotide sequence predicts a protein of 1023 amino acids (112 kDa) with 12 putative membrane-spanning regions, which is not related to other previously cloned sodium or chloride transporters. Northern hybridization shows two different gene products: a 3.7-kb mRNA localized only to the urinary bladder and a 3.0-kb mRNA present in several non-bladder/kidney tissues.
电中性的Na⁺:Cl⁻共转运系统参与许多重要的生理过程，包括上皮细胞的盐吸收与分泌以及细胞体积调节。一类Na⁺:Cl⁻共转运体受到噻嗪类利尿剂的特异性抑制，并且基于对钾离子需求的缺乏以及对布美他尼等氨磺酰苯甲酸类利尿剂不敏感，可与Na⁺:K⁺:2Cl⁻共转运体区分开来。我们在此报告，利用表达克隆策略从冬比目鱼膀胱中分离出一个编码噻嗪敏感型电中性氯化钠共转运体的cDNA。克隆的共转运体的药理学和动力学特性与硬骨鱼膀胱和哺乳动物肾远曲小管上皮细胞中天然的噻嗪敏感型氯化钠共转运体的特性一致。核苷酸序列预测该蛋白由1023个氨基酸组成（112 kDa），具有12个假定的跨膜区域，与其他先前克隆的钠或氯转运体无关。Northern杂交显示出两种不同的基因产物：一种3.7 kb的mRNA仅定位于膀胱，另一种3.0 kb的mRNA存在于几种非膀胱/肾脏组织中。
