Gamma delta (γδ) T cells, a unique T cell subgroup, are crucial in various immune responses and immunopathology^1-3. The γδ T cell receptor (TCR), generated by γδ T cells, recognizes a diverse range of antigens independently of the major histocompatibility complex². The γδ TCR associates with CD3 subunits, initiating T cell activation and holding great potential in immunotherapy⁴. Here, we report the structures of two prototypical human Vγ9Vδ2 and Vγ5Vδ1 TCR–CD3 complexes^5,6, unveiling two distinct assembly mechanisms that depend on Vγ usage. The Vγ9Vδ2 TCR–CD3 complex is monomeric, with considerable conformational flexibility in the TCRγ/TCRδ extracellular domain (ECD) and connecting peptides (CPs). The length of CPs regulates the ligand association and T cell activation. Additionally, a cholesterol-like molecule wedges into the transmembrane region, exerting an inhibitory role in TCR signaling. The Vγ5Vδ1 TCR–CD3 complex displays a dimeric architecture, where two protomers nestle back-to-back via their Vγ5 domains of TCR ECDs. Our biochemical and biophysical assays further corroborate the dimeric structure. Importantly, the dimeric form of the Vγ5Vδ1 TCR is essential for T cell activation. These findings reveal organizing principles of the γδ TCR–CD3 complex, providing insights into the γδ TCR unique properties and facilitating immunotherapeutic interventions.

γδ (γδ) T 细胞是一种独特的 T 细胞亚群，在各种免疫反应和免疫病理学中至关重要^1-3。 γδ T 细胞受体 (TCR) 由 γδ T 细胞产生，可​​独立于主要组织相容性复合物识别多种抗原²。 γδ TCR 与 CD3 亚基结合，启动 T 细胞激活并在免疫治疗中具有巨大潜力⁴。在这里，我们报告了两种典型的人类 Vγ9Vδ2 和 Vγ5Vδ1 TCR-CD3 复合物的结构^5,6，揭示了两种依赖于 Vγ 使用的不同组装机制。 Vγ9Vδ2 TCR-CD3 复合物是单体，在 TCRγ/TCRδ 胞外结构域 (ECD) 和连接肽 (CP) 中具有相当大的构象灵活性。 CP 的长度调节配体结合和 T 细胞激活。此外，类胆固醇分子楔入跨膜区域，在 TCR 信号传导中发挥抑制作用。 Vγ5Vδ1 TCR-CD3 复合物显示出二聚体结构，其中两个原体通过 TCR ECD 的 Vγ5 结构域背对背地依偎在一起。我们的生化和生物物理测定进一步证实了二聚体结构。重要的是，Vγ5Vδ1 TCR 的二聚体形式对于 T 细胞激活至关重要。这些发现揭示了 γδ TCR-CD3 复合物的组织原理，提供了对 γδ TCR 独特特性的见解并促进免疫治疗干预。