Abstract The human protein Lynx2 belongs to the Ly6/uPAR family of “three-finger” proteins and is associated with the cell membrane by the glycosylphosphatidylinositol (GPI) anchor. Lynx2 is expressed in the brain areas responsible for anxiety level control: prefrontal cortex, basolateral tonsil, hippocampus, and medial dorsal nucleus of the thalamus; it probably participates in anxiety regulation by interaction with α4β2 nicotinic acetylcholine receptor. Currently, the nature of the Lynx2 interaction with the receptor is unknown. We developed a bacterial expression system for production of a Lynx2 water-soluble domain (ws-Lynx2). The protein was obtained in the form of E. coli cytoplasmic inclusion bodies, with subsequent solubilization under denaturing conditions and renaturation. Production of milligram quantities of the 13 С- 15 N-labeled variant of ws-Lynx2 made it possible to characterize the secondary structure of this protein by means of heteronuclear NMR spectroscopy. It was shown that ws-Lynx2 has structure typical for three-finger proteins from the Ly6/uPAR family with some unique features, such as helical elements in the first and third loops. Development of the effective recombinant production system opens up new horizons for further structural and functional studies of Lynx2.

中文翻译：

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人类神经调节剂 Lynx2 的细菌产生和结构研究

摘要 人蛋白 Lynx2 属于“三指”蛋白 Ly6/uPAR 家族，通过糖基磷脂酰肌醇 (GPI) 锚与细胞膜结合。Lynx2 在负责控制焦虑水平的大脑区域中表达：前额叶皮层、基底外侧扁桃体、海马和丘脑内侧背核；它可能通过与 α4β2 烟碱乙酰胆碱受体的相互作用参与焦虑调节。目前，Lynx2 与受体相互作用的性质尚不清楚。我们开发了一种用于生产 Lynx2 水溶性域 (ws-Lynx2) 的细菌表达系统。该蛋白质以大肠杆菌细胞质包涵体的形式获得，随后在变性条件下溶解和复性。ws-Lynx2 的 13 С- 15 N 标记变体的毫克量生产使得通过异核 NMR 光谱表征该蛋白质的二级结构成为可能。结果表明，ws-Lynx2 具有 Ly6/uPAR 家族三指蛋白的典型结构，具有一些独特的特征，例如第一个和第三个环中的螺旋元件。开发有效的重组生产系统为 Lynx2 的进一步结构和功能研究开辟了新的视野。