Divisions of Clinical Pharmacology/Toxicology, Department of Medicine, University Hospital, CH-8091, Zürich, Switzerland,
Cytotechnology. 2000 Oct;34(1-2):1-9. doi: 10.1023/A:1008152729133.
Sodium-dependent uptake of bile acids from blood is aliver-specific function which is mediated by theNa(+)-taurocholate cotransporting polypeptide(Ntcp). We report the stable expression of aNa(+)-taurocholate cotransporting green fluorescentfusion protein in the human hepatoblastoma cell lineHepG2, normally lacking Ntcp expression. Ntcp-EGFPassociated green fluorescence colocalized with Ntcpimmunofluorescence in the plasma membrane. Intransfected HepG2 cells, the fusion protein mediatedthe sodium-dependent uptake of the bile acidtaurocholate (K(m): 24.6 mumol/l) and of the anionicsteroids estrone-3-sulfate and dehydroepiandrosteronesulfate. We conclude that the Ntcp-EGFP fusion proteinfollows the sorting route of Ntcp, is functionallyidentical to Ntcp and could be used to monitor proteintrafficking in living HepG2 cells.
胆酸从血液中的钠依赖性摄取是肝脏特异性功能，由 Na(+)-牛磺胆酸钠共转运蛋白 (Ntcp) 介导。我们报告了人肝癌细胞系 HepG2 中稳定表达的 Na(+)-牛磺胆酸钠共转运绿色荧光融合蛋白，该细胞系通常缺乏 Ntcp 表达。Ntcp-EGFP 相关的绿色荧光与质膜中的 Ntcp 免疫荧光共定位。在转染的 HepG2 细胞中，融合蛋白介导了胆汁酸牛磺胆酸钠（K(m)：24.6 μmol/l）和阴离子甾体雌酮-3-硫酸盐和脱氢表雄酮硫酸盐的钠依赖性摄取。我们得出结论，Ntcp-EGFP 融合蛋白遵循 Ntcp 的分拣途径，与 Ntcp 在功能上相同，可用于监测活 HepG2 细胞中的蛋白质运输。
