Gap junctions provide a communication pathway between adjacent cells. They are formed by paired connexons that reside in the plasma membrane of their respective cell and their activity can be modulated by the bilayer composition. In this work, we study the dynamic behavior of a Cx26 connexon embedded in a POPC lipid bilayer, studying: the membrane protein interactions and the ion flux though the connexon pore. We analyzed extensive atomistic molecular dynamics simulations for different conditions, with and without calcium ions. We found that lipid-protein interactions were mainly mediated by hydrogen bonds. Specific amino acids were identified forming hydrogen bonds with the POPC lipids (ARG98, ARG127, ARG165, ARG216, LYS22, LYS221, LYS223, LYS224, SER19, SER131, SER162, SER219, SER222, THR18 and TYR97, TYR155, TYR212, and TYR217). In the presence of calcium ions, we found subtle differences on the HB lifetimes. Finally, these MD simulations are able to identify and explain differential chlorine flux through the pore depending on the presence or absence of the calcium ions and its distribution within the pore.

中文翻译：

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钙对嵌入POPC双层的Cx26连接子中脂质-蛋白质相互作用和离子通量的影响。

间隙连接提供相邻细胞之间的通信途径。它们由位于其各自细胞质膜中的成对的连接子形成，并且它们的活性可以由双层组合物调节。在这项工作中，我们研究了嵌入POPC脂质双层中的Cx26连接子的动力学行为，研究了：膜蛋白相互作用和通过连接子孔的离子通量。我们分析了在有和没有钙离子的情况下，针对不同条件进行的大量原子分子动力学模拟。我们发现脂蛋白相互作用主要由氢键介导。确定了与POPC脂质形成氢键的特定氨基酸（ARG98，ARG127，ARG165，ARG216，LYS22，LYS221，LYS223，LYS224，SER19，SER131，SER162，SER219，SER222，THR18和TYR97，TYR155，TYR212和TYR217） 。在存在钙离子的情况下，我们发现HB寿命存在细微差别。最终，这些MD模拟能够根据钙离子的存在与否及其在孔中的分布来识别和解释通过孔的不同氯通量。