兔心脏中氯离子通道蛋白2α（ClC-2G）新型截短形式（ClC-2β）的分子克隆与特性分析

Molecular cloning and characterization of a novel truncated from (ClC-2 beta) of ClC-2 alpha (ClC-2G) in rabbit heart.

作者信息

Furukawa T, Horikawa S, Terai T, Ogura T, Katayama Y, Hiraoka M

机构信息

Department of Autonomic Physiology, School of Medicine, Tokyo Medical and Dental University, Japan.

出版信息

FEBS Lett. 1995 Nov 13;375(1-2):56-62. doi: 10.1016/0014-5793(95)01178-h.

DOI:10.1016/0014-5793(95)01178-h

PMID:7498481

Abstract

Two cDNAs encoding rabbit heart Cl- channels (rabClC-2 beta and rabClC-2 alpha) were isolated by a PCR cloning strategy. RabClC-2 beta is a novel cDNA consisting of 2998 bp and encoding the 822-amino acid protein, while rabClC-2 alpha is identical to previously reported ClC-2G. RabClC-2 beta is 68 amino acids truncated from NH2-terminus of rabClC-2 alpha, but all 13 putative hydrophobic domains are conserved in rabClC-2 beta. Although rabClC-2 alpha was suggested to be activated by extracellular hypotonicity, expression of rabClC-2 beta in Xenopus oocytes induced large Cl- currents even in the absence of extracellular hypotonicity. Induction of external hypotonicity did not further increase the amplitude of membrane currents. On the other hand, as similar to rabClC-2 alpha, rabClC-2 beta current was augmented by PKA activation. Thus, different RNA processing of the same gene appears to provide two highly homologous PKA-activated Cl- channels with or without responsiveness to cell swelling in rabbit heart.

摘要

通过聚合酶链反应（PCR）克隆策略分离出两个编码兔心脏氯离子通道的互补DNA（rabClC - 2β和rabClC - 2α）。RabClC - 2β是一个新的互补DNA，由2998个碱基对组成，编码822个氨基酸的蛋白质，而rabClC - 2α与先前报道的ClC - 2G相同。RabClC - 2β从rabClC - 2α的氨基末端截短了68个氨基酸，但rabClC - 2β中所有13个假定的疏水结构域都是保守的。尽管rabClC - 2α被认为可被细胞外低渗激活，但即使在没有细胞外低渗的情况下，rabClC - 2β在非洲爪蟾卵母细胞中的表达也能诱导出大的氯离子电流。诱导细胞外低渗并没有进一步增加膜电流的幅度。另一方面，与rabClC - 2α相似，rabClC - 2β电流可被蛋白激酶A（PKA）激活增强。因此，同一基因的不同RNA加工似乎为兔心脏提供了两个高度同源的、可被PKA激活的氯离子通道，其中一个对细胞肿胀有反应，另一个则没有。