Receptor tyrosine kinase like orphan receptor 2 (ROR2) is a co-receptor for some Wnt proteins including Wnt5a that activate the noncanonical Wnt/planar cell polarity (PCP) signaling pathway. Upregulation of ROR2 is associated with several cancer forms. The extracellular region of ROR2, which contains an immunoglobulin (Ig)-like domain, a Frizzled like cysteine-rich domain (CRD) and a Kringle domain, is a potential anticancer drug target. The structural and biochemical properties of the ROR2 extracellular region remain largely unexplored. Here we describe the mapping and purification, using a baculovirus - insect cell system, of a near-full-length ROR2 extracellular fragment (residues 53-402), which is well-behaved and suitable for future structural and biochemical analysis. We show that the extracellular region of ROR2 per se is monomeric in solution. Different monoclonal antibodies raised against the purified ROR2 protein can specifically recognize the protein and can either inhibit or activate the PCP activity in a cell-based assay, and are thus potentially useful for future mechanistic and therapeutic/diagnostic studies. The biological relevance of these antibodies further demonstrates that the purified recombinant ROR2 protein is properly folded and biochemically active.

中文翻译：

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人类受体酪氨酸激酶样孤儿受体2（ROR2）的细胞外区域的纯化和表征。

受体酪氨酸激酶样孤儿受体2（ROR2）是某些Wnt蛋白（包括Wnt5a）的共受体，该蛋白激活非规范性Wnt /平面细胞极性（PCP）信号传导途径。ROR2的上调与几种癌症形式有关。ROR2的细胞外区域是潜在的抗癌药物靶标，其中包含免疫球蛋白（Ig）样域，卷曲的类半胱氨酸富集域（CRD）和Kringle域。ROR2细胞外区域的结构和生化特性仍未开发。在这里，我们描述了使用杆状病毒-昆虫细胞系统绘制和纯化接近全长的ROR2细胞外片段（残基53-402）的方法，该片段的行为举止良好，适合将来的结构和生化分析。我们表明，ROR2的胞外区域本身在溶液中是单体的。针对纯化的ROR2蛋白产生的不同单克隆抗体可以特异性识别该蛋白，并且可以在基于细胞的测定法中抑制或激活PCP活性，因此潜在地可用于未来的机制和治疗/诊断研究。这些抗体的生物学相关性进一步表明，纯化的重组ROR2蛋白已正确折叠并具有生化活性。