排斥引导分子 b (RGMb) 是 RGM 家族中糖基磷脂酰肌醇锚定的成员，最初被确定为神经系统中骨形态发生蛋白 (BMP) 的共受体。 RGMb的表达受到背根神经节11（DRG11）的转录调节，DRG11是在胚胎DRG和背角神经元中表达的转录因子，在感觉回路的发育中发挥重要作用。 RGMb参与胚胎发育、免疫反应、细胞间粘附和肿瘤发生等重要生理过程。此外，RGMb主要参与RGMb-neogenin-Rho和BMP信号通路的调节。最近发现的程序性死亡配体2（PD-L2）-RGMb结合揭示了以RGMb为中心的细胞信号网络和功能调控极其复杂。最新报告表明，肠道微生物群中 PD-L2-RGMb 通路的下调可促进抗肿瘤免疫反应，这定义了一种潜在有效的免疫策略。然而，RGMb在多种人类疾病中的生物学功能尚未完全确定，仍将是一个活跃的研究领域。本文综述了 RGMb 的性质和功能，重点介绍了其在各种生理和病理条件下的作用。

Repulsive guidance molecule b (RGMb), a glycosylphosphatidylinositol-anchored member of the RGM family, is initially identified as a co-receptor of bone morphogenetic protein (BMP) in the nervous system. The expression of RGMb is transcriptionally regulated by dorsal root ganglion 11 (DRG11), which is a transcription factor expressed in embryonic DRG and dorsal horn neurons and plays an important role in the development of sensory circuits. RGMb is involved in important physiological processes such as embryonic development, immune response, intercellular adhesion and tumorigenesis. Furthermore, RGMb is mainly involved in the regulation of RGMb-neogenin-Rho and BMP signalling pathways. The recent discovery of programmed death-ligand 2 (PD-L2)-RGMb binding reveals that the cell signalling network and functional regulation centred on RGMb are extremely complex. The latest report suggests that down-regulation of the PD-L2-RGMb pathway in the gut microbiota promotes an anti-tumour immune response, which defines a potentially effective immune strategy. However, the biological function of RGMb in a variety of human diseases has not been fully determined, and will remain an active research field. This article reviews the properties and functions of RGMb, focusing on its role under various physiological and pathological conditions.