Poulsen Asser Nyander, Klaerke Dan Arne
Department of Physiology and Biochemistry, IBHV, Faculty of Life Sciences, University of Copenhagen, Groennegaardsvej 7, 1870 Frederiksberg C, Denmark.
Biochem Biophys Res Commun. 2007 Nov 9;363(1):133-9. doi: 10.1016/j.bbrc.2007.08.146. Epub 2007 Aug 31.
The KCNE1 beta-subunit is a modulatory one-trans-membrane segment accessory protein that alters KCNQ1 K(+) channel current characteristics, though it is not required for channel expression. The KCNE1 and KCNQ1 interaction was investigated by looking for effects of expression time on channel currents in Xenopus laevis oocytes. We found that long-time expression of KCNQ1+KCNE1 (2-14 days) resulted in gradual changes in current characteristics resembling a disappearance of KCNE1 from the oocyte plasma membrane. Towards the end of the expression period the current of oocytes expressing KCNQ1+KCNE1 was indistinguishable from those expressing KCNQ1 alone. No time dependent effect was seen in oocytes expressing KCNQ1 alone or a concatamer of KCNQ1 and KCNE1. Brefeldin A was tested, showing that measured current was independent of exocytosis (decreased capacitance) thus eliminating a continuous displacement-explanation. Based on the functional data, we suggest that the interaction between KNCE1 and KCNQ1 may be reversible and transient in a "Kiss & Go" manner, supporting a physiological role for KCNE1 as a dynamic regulatory molecule.
KCNE1β亚基是一种具有一个跨膜片段的调节性辅助蛋白，它能改变KCNQ1钾通道的电流特性，不过通道表达并不需要它。通过研究非洲爪蟾卵母细胞中表达时间对通道电流的影响，来探究KCNE1与KCNQ1之间的相互作用。我们发现，KCNQ1+KCNE1的长时间表达（2-14天）会导致电流特性逐渐变化，类似于KCNE1从卵母细胞质膜上消失。在表达期结束时，表达KCNQ1+KCNE1的卵母细胞电流与仅表达KCNQ1的卵母细胞电流无法区分。在单独表达KCNQ1或表达KCNQ1与KCNE1串联体的卵母细胞中未观察到时间依赖性效应。对布雷菲德菌素A进行了测试，结果表明测得的电流与胞吐作用（电容降低）无关，从而排除了持续置换的解释。基于功能数据，我们认为KNCE1与KCNQ1之间的相互作用可能以“亲吻即走”的方式可逆且短暂，这支持了KCNE1作为动态调节分子的生理作用。
