Laub Katrine R, Witschas Katja, Blicher Andreas, Madsen Søren B, Lückhoff Andreas, Heimburg Thomas
Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark.
Biochim Biophys Acta. 2012 May;1818(5):1123-34. doi: 10.1016/j.bbamem.2012.01.014. Epub 2012 Jan 28.
In this article we compare electrical conductance events from single channel recordings of three TRP channel proteins (TRPA1, TRPM2 and TRPM8) expressed in human embryonic kidney cells with channel events recorded on synthetic lipid membranes close to melting transitions. Ion channels from the TRP family are involved in a variety of sensory processes including thermo- and mechano-reception. Synthetic lipid membranes close to phase transitions display channel-like events that respond to stimuli related to changes in intensive thermodynamic variables such as pressure and temperature. TRP channel activity is characterized by typical patterns of current events dependent on the type of protein expressed. Synthetic lipid bilayers show a wide spectrum of electrical phenomena that are considered typical for the activity of protein ion channels. We find unitary currents, burst behavior, flickering, multistep-conductances, and spikes behavior in both preparations. Moreover, we report conductances and lifetimes for lipid channels as described for protein channels. Non-linear and asymmetric current-voltage relationships are seen in both systems. Without further knowledge of the recording conditions, no easy decision can be made whether short current traces originate from a channel protein or from a pure lipid membrane.
在本文中，我们将在人胚胎肾细胞中表达的三种瞬时受体电位（TRP）通道蛋白（TRPA1、TRPM2和TRPM8）的单通道记录的电导事件，与在接近熔化转变的合成脂质膜上记录的通道事件进行比较。TRP家族的离子通道参与多种感觉过程，包括热感受和机械感受。接近相变的合成脂质膜表现出类似通道的事件，这些事件对与强度热力学变量（如压力和温度）变化相关的刺激作出反应。TRP通道活性的特征在于取决于所表达蛋白质类型的典型电流事件模式。合成脂质双层显示出广泛的电现象，这些现象被认为是蛋白质离子通道活性的典型现象。我们在两种制剂中都发现了单位电流、爆发行为、闪烁、多步电导和尖峰行为。此外，我们报告了脂质通道的电导和寿命，就像对蛋白质通道所描述的那样。在两个系统中都观察到了非线性和不对称的电流-电压关系。如果没有关于记录条件的进一步知识，就很难确定短电流轨迹是源自通道蛋白还是纯脂质膜。
