Axon guidance relies on a combinatorial code of receptor and ligand interactions that direct adhesive/attractive and repulsive cellular responses. Recent structural data have revealed many of the molecular mechanisms that govern these interactions and enabled the design of sophisticated mutant tools to dissect their biological functions. Here, we discuss the structure/function relationships of four major classes of guidance cues (ephrins, semaphorins, slits, netrins) and examples of morphogens (Wnt, Shh) and of cell adhesion molecules (FLRT). These cell signaling systems rely on specific modes of receptor-ligand binding that are determined by selective binding sites; however, defined structure-encoded receptor promiscuity also enables cross talk between different receptor/ligand families and can also involve extracellular matrix components. A picture emerges in which a multitude of highly context-dependent structural assemblies determines the finely tuned cellular behavior required for nervous system development.

中文翻译：

---

轴突指导的结构性观点。

轴突的指导依赖于受体和配体相互作用的组合代码，该代码指导粘附/吸引和排斥细胞反应。最近的结构数据已经揭示了控制这些相互作用的许多分子机制，并使设计复杂的突变体工具能够剖析它们的生物学功能。在这里，我们讨论了四种主要的指导线索（ephrins，semaphorin，slits，netrins）的结构/功能关系，以及形态发生子（Wnt，Shh）和细胞粘附分子（FLRT）的示例。这些细胞信号系统依赖于受体-配体结合的特定模式，该模式由选择性结合位点决定。然而，定义的结构编码的受体混杂性也使得不同的受体/配体家族之间能够发生串扰，并且还可能涉及细胞外基质成分。