Ludwig J, Terlau H, Wunder F, Brüggemann A, Pardo L A, Marquardt A, Stühmer W, Pongs O
ZMNH, Institut für neurale Signalverarbeitung, Hamburg, Germany.
EMBO J. 1994 Oct 3;13(19):4451-8. doi: 10.1002/j.1460-2075.1994.tb06767.x.
We have cloned a mammalian (rat) homologue of Drosophila ether á go-go (eag) cDNA, which encodes a distinct type of voltage activated potassium (K) channel. The derived Drosophila and rat eag polypeptides share > 670 amino acids, with a sequence identity of 61%, exhibiting a high degree of similarity at the N-terminus, the hydrophobic core including the pore forming P region and a potential cyclic nucleotide binding site. Rat eag mRNA is specifically expressed in the central nervous system. In the Xenopus oocyte expression system rat eag mRNA gives rise to voltage activated K channels which have distinct properties in comparison with Drosophila eag channels and other voltage activated K channels. Thus, the rat eag channel further extends the known diversity of K channels. Most notably, the kinetics of rat eag channel activation depend strongly on holding membrane potential. Hyperpolarization slows down the kinetics of activation; conversely depolarization accelerates the kinetics of activation. This novel K channel property may have important implications in neural signal transduction allowing neurons to tune their repolarizing properties in response to membrane hyperpolarization.
我们克隆了果蝇“醚 - 去 - 去”（eag）cDNA的哺乳动物（大鼠）同源物，它编码一种独特类型的电压激活钾（K）通道。推导得到的果蝇和大鼠eag多肽共有超过670个氨基酸，序列同一性为61%，在N端、包括形成孔道的P区域的疏水核心以及一个潜在的环核苷酸结合位点表现出高度相似性。大鼠eag mRNA在中枢神经系统中特异性表达。在非洲爪蟾卵母细胞表达系统中，大鼠eag mRNA产生电压激活K通道，与果蝇eag通道和其他电压激活K通道相比，这些通道具有不同的特性。因此，大鼠eag通道进一步扩展了已知的K通道多样性。最值得注意的是，大鼠eag通道激活的动力学强烈依赖于膜电位的保持。超极化会减慢激活的动力学；相反，去极化会加速激活的动力学。这种新型K通道特性可能在神经信号转导中具有重要意义，使神经元能够根据膜超极化调整其复极化特性。
