Expression of distinct ERG proteins in rat, mouse, and human heart -: Relation to functional IKr channels
Expression of distinct ERG proteins in rat, mouse, and human heart -: Relation to functional IKr channels
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DOI：
10.1074/jbc.275.8.5997
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发表时间：
2000-02-25
影响因子：
4.8
通讯作者：
Nerbonne, JM
中科院分区：
文献类型：
--
作者：
Pond, AL;Scheve, BK;Nerbonne, JM
遗传性长QT综合征的一种形式，LQT 2，是由HERG 1突变引起的，HERG 1是人类ether-a-go-go相关基因，编码电压门控K+通道α亚基。HERG 1的异源性表达产生与心肌细胞中延迟整流的快速组分I-Kr相似（但不相同）的K+电流。此外，HERG 1和MERG 1（小鼠ERG 1）的N-末端剪接变体（称为HERG 1b和NIERG 1b）已被克隆，并被认为在功能性I-Kr通道的产生中发挥作用。在这里的实验中，针对HERG 1产生的抗体用于检查心脏和大脑中的ERG 1蛋白表达。在表达HERG 1、MERG 1、dr RERG 1（大鼠ERG 1）的QT-6细胞提取物的Western印迹中，用靶向HERG 1 C末端的抗体进行探测，鉴定出单个155-kDa蛋白，而在表达MERG 1b或HEBG 1b的细胞提取物的印迹中，95-kDa条带明显。然而，在分级大鼠（和小鼠）的大脑和心脏膜蛋白的免疫印迹，两个突出的高分子量蛋白165和205 kDa的检测。用糖肽酶F处理后，165和205 kDa蛋白被175和130 kDa的两条新条带取代，表明ERG 1在大鼠/小鼠脑和心脏中的糖基化差异。在人类心脏中，明显存在表观分子量为145 kDa的单一HERG 1蛋白。在大鼠中，ERG 1蛋白（和I-Kr）在心房中的表达高于心室，而在人类中，HERG 1在心室组织中的表达高于心房组织。总之，这些结果表明，N-末端选择性剪接的ERG 1（即ERG 1b）的变体不表达在大鼠，小鼠或人类心脏的蛋白质水平，这些变体不，因此，在功能性心脏I-Kr通道的产生中发挥作用。
One form of inherited long QT syndrome, LQT2, results from mutations in HERG1, the human ether-a-go-go-related gene, which encodes a voltage-gated K+ channel alpha subunit. Heterologous expression of HERG1 gives rise to K+ currents that are similar (but not identical) to the rapid component of delayed rectification, I-Kr in cardiac myocytes, In addition, N-terminal splice variants of HERG1 and MERG1 (mouse ERG1) referred to as HERG1b and NIERG1b have been cloned and suggested to play roles in the generation of functional I-Kr channels. In the experiments here, antibodies generated against HERG1 were used to examine ERG1 protein expression in heart and in brain. In Western blots of extracts of QT-6 cells expressing HERG1, MERG1, dr RERG1 (rat ERG1) probed with antibodies targeted against the C terminus of HERG1, a single 155-kDa protein is identified, whereas a 95-kDa band is evident in blots of extracts from cells expressing MERG1b or HEBG1b. In immunoblots of fractionated rat (and mouse) brain and heart membrane proteins, however, two prominent high molecular mass proteins of 165 and 205 kDa were detected. Following treatment with glycopeptidase F, the 165- and 205-kDa proteins were replaced by two new bands at 175 and 130 kDa, suggesting that ERG1 is differentially glycosylated in rat/mouse brain and heart. In human heart, a single HERG1 protein with an apparent molecular mass of 145 kDa is evident. In rats, ERG1 protein (and I-Kr) expression is higher in atria than ventricles, whereas in humans, HERG1 expression is higher in ventricular, than atrial, tissue. Taken together, these results suggest that the N-terminal alternatively spliced variants of ERG1 (i.e. ERG1b) are not expressed at the protein level in rat, mouse, or human heart and that these variants do not, therefore, play roles in the generation of functional cardiac I-Kr channels.