Assembly and suppression of endogenous Kv1.3 channels in human T cells.
Assembly and suppression of endogenous Kv1.3 channels in human T cells.
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DOI：
10.1085/jgp.107.3.409
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发表时间：
1996-03
期刊：
影响因子：
--
通讯作者：
Deutsch C
中科院分区：
文献类型：
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作者：
Panyi G;Deutsch C
人T淋巴细胞中的主要K+通道是Kv1.3，其通过C型机制失活。为了研究这些四聚体通道在人T淋巴细胞系Jurkat中的组装，我们表征了内源性野生型（WT）Kv1.3亚基和异源表达的突变型（A413V）Kv1.3亚基之间异源四聚体通道的形成。我们使用的同源四聚体通道和异源四聚体通道产生的电流的C型失活的动力学分析，以确定不同的亚基化学计量的通道的分布。分布通过二项式分布或二项式分布加上WT同源四聚体的一部分来充分描述，表明亚基组装是随机过程，并且质膜中表达的四聚体不会解离和重新组装。此外，内源性Kv1.3电流被异源表达的截短Kv1.3抑制，该截短Kv1.3包含氨基末端和前两个跨膜片段。在转染后48小时达到最大抑制的时间过程与异源表达的A413 V和内源性WT通道之间形成异源四聚体的时间间隔重叠。我们的研究结果表明，在一个细胞中的K+通道亚型的多样性是由空间分离的单体池，而是由时间重叠的程度和亚基表达的动力学。
The predominant K+ channel in human T lymphocytes is Kv1.3, which inactivates by a C-type mechanism. To study assembly of these tetrameric channels in Jurkat, a human T-lymphocyte cell line, we have characterized the formation of heterotetrameric channels between endogenous wild-type (WT) Kv1.3 subunits and heterologously expressed mutant (A413V) Kv1.3 subunits. We use a kinetic analysis of C-type inactivation of currents produced by homotetrameric channels and heterotetrameric channels to determine the distribution of channels with different subunit stoichiometries. The distributions are well- described by either a binomial distribution or a binomial distribution plus a fraction of WT homotetramers, indicating that subunit assembly is a random process and that tetramers expressed in the plasma membrane do not dissociate and reassemble. Additionally, endogenous Kv1.3 current is suppressed by a heterologously expressed truncated Kv1.3 that contains the amino terminus and the first two transmembrane segments. The time course for suppression, which is maximal at 48 h after transfection, overlaps with the time interval for heterotetramer formation between heterologously expressed A413V and endogenous WT channels. Our findings suggest that diversity of K+ channel subtypes in a cell is regulated not by spatial segregation of monomeric pools, but rather by the degree of temporal overlap and the kinetics of subunit expression.