Sakamoto H, Kawasaki M, Uchida S, Sasaki S, Marumo F
Second Department of Internal Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113, Japan.
J Biol Chem. 1996 Apr 26;271(17):10210-6. doi: 10.1074/jbc.271.17.10210.
A new outwardly rectifying Cl- channels (ORCC) that belongs to ClC Cl- channel family has been identified from rat kidney and designated as ClC-5. ClC-5 cDNA encodes a polypeptide of 746 amino acids, which is indicated by hydrophobicity analysis to have structural features that are common of the ClC family. However, the amino acid sequence was weakly homologous to those of other ClC Cl- channels except for ClC-3, which we recently identified as a Ca2+-sensitive ORCC. Northern blot analysis of rat tissues showed that ClC-5 mRNA was predominantly expressed in the kidney and colon. To characterize the functional properties of ClC-5 by whole cell patch-clamp technique, we established the stably transfected CHO-K1 cell line using intranuclear microinjection technique. The transfected cells induced outwardly rectifying and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-sensitive Cl- currents on whole cell configuration. Following the identification of two highly homologous ORCCs, ClC-3 and ClC-5, a new subfamily encoding ORCC has emerged in the ClC family. Furthermore, ClC-5 was almost identical to a partial sequence of human cDNA that is related to Dent's disease. The molecular structure and functional properties of ClC-5 will provide an important insight into ORCCs and the pathogenesis of Dent's disease.
一种属于ClC氯离子通道家族的新型外向整流氯离子通道（ORCC）已从大鼠肾脏中鉴定出来，并命名为ClC-5。ClC-5 cDNA编码一个由746个氨基酸组成的多肽，疏水性分析表明其具有ClC家族共有的结构特征。然而，除了我们最近鉴定为对Ca2+敏感的ORCC的ClC-3外，该氨基酸序列与其他ClC氯离子通道的序列同源性较弱。对大鼠组织的Northern印迹分析表明，ClC-5 mRNA主要在肾脏和结肠中表达。为了通过全细胞膜片钳技术表征ClC-5的功能特性，我们使用核内显微注射技术建立了稳定转染的CHO-K1细胞系。在全细胞配置下，转染细胞诱导出外向整流且对4,4'-二异硫氰基芪-2,2'-二磺酸敏感的氯离子电流。在鉴定出两个高度同源的ORCC（ClC-3和ClC-5）之后，ClC家族中出现了一个编码ORCC的新亚家族。此外，ClC-5与一种与丹特病相关的人类cDNA的部分序列几乎相同。ClC-5的分子结构和功能特性将为ORCC以及丹特病的发病机制提供重要的见解。
