The neuropeptide 26RFa plays important roles in the regulation of many physiological functions. 26RFa has been recognized as an endogenous ligand for receptor GPR103. In the present study, we demonstrate that GPR103 dually couples to Gαq and Gαi/o proteins. However, two naturally occurring missense mutations were identified from a young male patient. In the first, Y68H, induction of Ca²⁺ mobilization was noted without detection of ERK1/2 activation. In the second, R371W, the potential to activate ERK1/2 signaling was retained but with failure to evoke Ca²⁺ mobilization. Further analysis provides evidence that Gαq, L-type Ca²⁺ channel and PKCβI and βII are involved in the Y68H-mediated signaling pathway, whereas Gαi/o, Gβγ, and PKCζ are implicated in the R371W-induced signaling. Our results demonstrate that two point mutations, Y68H and R371W, affect the equilibrium between the different receptor conformations, leading to alteration of G protein-coupling preferences. Importantly, these findings provide a foundation for future elucidation of GPCR-mediated biased signaling and the physiological implications of their bias.

神经肽 26RFa 在许多生理功能的调节中起着重要作用。26RFa 已被认为是受体 GPR103 的内源性配体。在本研究中，我们证明 GPR103 与 Gαq 和 Gαi/o 蛋白双重偶联。然而，从一名年轻男性患者身上发现了两个自然发生的错义突变。在第一个 Y68H 中，注意到Ca ²⁺动员的诱导而没有检测到 ERK1/2 激活。在第二个 R371W 中，激活 ERK1/2 信号传导的潜力被保留，但未能引起 Ca ²⁺动员。进一步的分析提供证据表明 Gαq, L-type Ca ²⁺通道和 PKCβI 和 βII 参与 Y68H 介导的信号通路，而 Gαi/o、Gβγ 和 PKCζ 参与 R371W 诱导的信号传导。我们的结果表明，Y68H 和 R371W 两个点突变影响不同受体构象之间的平衡，导致 G 蛋白偶联偏好的改变。重要的是，这些发现为未来阐明 GPCR 介导的偏向信号及其偏向的生理意义奠定了基础。