Dimeric cystic fibrosis transmembrane conductance regulator exists in the plasma membrane.
Dimeric cystic fibrosis transmembrane conductance regulator exists in the plasma membrane.
复制标题
二聚体囊性纤维化跨膜电导调节剂存在于质膜中。
作者：
M. Ramjeesingh;J. Kidd;L. Huan;Yanchun Wang;C. Bear
CFTR（囊性纤维化跨膜传导调节因子）介导氯离子传导穿过上皮细胞的顶膜，CFTR的突变导致上皮细胞液体转运缺陷。最近，有相当大的兴趣，在确定的四级结构的CFTR在细胞表面，因为这样的信息是一个关键，以了解分子基础的发病机制，在患者窝藏致病突变。在我们以前的工作中[Ramjeesingh，Li，Kogan，Wang，Huan和Bear（2001）Biochemistry 40，10700-10706]，我们表明单体CFTR是蛋白质的最小功能形式，然而当使用杆状病毒系统在Sf 9细胞中表达时，它也以二聚体存在。本研究的目的是确定二聚体CFTR是否存在于哺乳动物细胞表面，特别是上皮细胞中。从由稳定表达CFTR的中国仓鼠卵巢细胞和T84上皮细胞制备的膜中溶解的CFTR，当通过凝胶过滤进行大小测定和通过非解离电泳进行分析时，如单体、二聚体和较大复合物所预测的那样迁移。质膜的纯化导致CFTR二聚体的富集，并且这种结构作为蛋白质的复杂糖基化形式存在，支持二聚体CFTR是生理学相关的概念。与其在质膜中的定位一致，通过表面生物素化标记二聚体CFTR。此外，通过应用膜不可渗透的化学交联剂，在完整上皮细胞的顶端表面捕获二聚体CFTR。因此，从本研究得出CFTR二聚体存在于上皮细胞的表面。进一步的研究是必要的，以了解二聚化对野生型和突变CFTR蛋白的细胞生物学的影响。
CFTR (cystic fibrosis transmembrane conductance regulator) mediates chloride conduction across the apical membrane of epithelia, and mutations in CFTR lead to defective epithelial fluid transport. Recently, there has been considerable interest in determining the quaternary structure of CFTR at the cell surface, as such information is a key to understand the molecular basis for pathogenesis in patients harbouring disease-causing mutations. In our previous work [Ramjeesingh, Li, Kogan, Wang, Huan and Bear (2001) Biochemistry 40, 10700-10706], we showed that monomeric CFTR is the minimal functional form of the protein, yet when expressed in Sf 9 cells using the baculovirus system, it also exists as dimers. The purpose of the present study was to determine if dimeric CFTR exists at the surface of mammalian cells, and particularly in epithelial cells. CFTR solubilized from membranes prepared from Chinese-hamster ovary cells stably expressing CFTR and from T84 epithelial cells migrates as predicted for monomeric, dimeric and larger complexes when subjected to sizing by gel filtration and analysis by non-dissociative electrophoresis. Purification of plasma membranes led to the enrichment of CFTR dimers and this structure exists as the complex glycosylated form of the protein, supporting the concept that dimeric CFTR is physiologically relevant. Consistent with its localization in plasma membranes, dimeric CFTR was labelled by surface biotinylation. Furthermore, dimeric CFTR was captured at the apical surface of intact epithelial cells by application of a membrane-impermeable chemical cross-linker. Therefore it follows from the present study that CFTR dimers exist at the surface of epithelial cells. Further studies are necessary to understand the impact of dimerization on the cell biology of wild-type and mutant CFTR proteins.
CFTR 氯离子通道的丧失会改变体外囊性纤维化气道上皮对盐的吸收。
影响因子：
16
作者：
Zabner,J;Smith,JJ;Karp,PH;Widdicombe,JH;Welsh,MJ
通讯作者：
Welsh,MJ