编码心脏内向整流钾通道的人类基因hIRK1的克隆与功能表达。

Cloning and functional expression of a human gene, hIRK1, encoding the heart inward rectifier K+-channel.

作者信息

Wood L S, Tsai T D, Lee K S, Vogeli G

机构信息

Upjohn Laboratories, Kalamazoo, MI 49001, USA.

出版信息

Gene. 1995 Oct 3;163(2):313-7. doi: 10.1016/0378-1119(95)00244-z.

DOI:10.1016/0378-1119(95)00244-z

PMID:7590287

Abstract

We have isolated a cDNA clone encoding a human inward rectifier potassium channel (hIRK1). The nucleotide (nt) sequence of the coding region is 88% similar to the mouse clone with only seven amino-acid (aa) differences. The hIRK1 cRNA initially expressed low levels of protein in a wheat germ system and in Xenopus oocytes. The addition of a SmaI site 3' to the poly(A) tail increased the expression at least tenfold. Xenopus oocytes injected with the hIRK1 cRNA developed resting potentials that averaged -96 mV and a large inward current that was blocked by Ba2+ or Cs+. The hIRK1 EK shifted 54.6 mV per decade change in [K]o, and its channel conductance increased with [K]o by a 0.3 exponent factor. Above EK, the hIRK1 I-V relation has a distinct 'N'-shape. Cell-attached single-channel conductance in 140 mM K+ pipette solution averaged 29 pS. The negative resting potential and the 'N'-shape I-V relation of hIRK1 closely resemble that of the native cardiac inward rectifier IK1.

摘要

我们分离出了一个编码人类内向整流钾通道（hIRK1）的cDNA克隆。编码区的核苷酸（nt）序列与小鼠克隆的相似性为88%，仅有7个氨基酸（aa）差异。hIRK1的cRNA最初在麦胚系统和非洲爪蟾卵母细胞中表达的蛋白水平较低。在多聚腺苷酸（poly(A)）尾的3'端添加一个SmaI位点使表达至少增加了10倍。注射了hIRK1 cRNA的非洲爪蟾卵母细胞产生的静息电位平均为-96 mV，并产生了一个被Ba2+或Cs+阻断的大内向电流。hIRK1的EK随[K]o每十年变化54.6 mV而移动，其通道电导随[K]o以0.3的指数因子增加。在EK之上，hIRK1的电流-电压（I-V）关系呈明显的“N”形。在140 mM K+移液管溶液中，细胞贴附式单通道电导平均为29 pS。hIRK1的负静息电位和“N”形I-V关系与天然心脏内向整流IK1非常相似。