Alternative splicing enables G protein-coupled receptor (GPCR) genes to greatly increase the number of structurally and functionally distinct receptor isoforms. However, the functional role and relevance of the individual GPCR splice variants in regulating physiological processes are still to be assessed. A naturally occurring alternative splice variant of Bombyx CAPA-PVK receptor, BomCAPA-PVK-R1-Δ341, has been shown to act as a dominant-negative protein to regulate cell surface expression and function of the canonical CAPA-PVK receptor. Herein, using functional assays, we identify the splice variant Δ341 as a specific receptor for neuropeptide CAPA-PK, and upon activation, Δ341 signals to ERK1/2 pathway. Further characterization demonstrates that Δ341 couples to Gαi/o, distinct from the Gαq-coupled canonical CAPA-PVK receptor, triggering ERK1/2 phosphorylation through Gβγ-PI3K-PKCζ signaling cascade. Moreover, our ELISA data show that the ligand-dependent internalization of the splice variant Δ341 is significantly impaired due to lack of GRKs-mediated phosphorylation sites. Our findings highlight the potential of this knowledge for molecular, pharmacological and physiological studies on GPCR splice variants in the future.

中文翻译：

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Gαq偶联家禽CAPA-PVK受体1的新型剪接变体充当CAPA-PK的特异性Gαi/ o联结受体。

选择性剪接使G蛋白偶联受体（GPCR）基因大大增加了结构和功能上不同的受体同工型的数量。但是，单个GPCR剪接变体在调节生理过程中的功能作用和相关性仍有待评估。已经显示出Bombyx CAPA-PVK受体的天然替代剪接变体BomCAPA-PVK-R1-Δ341作为显性负性蛋白，可调节经典CAPA-PVK受体的细胞表面表达和功能。在这里，我们使用功能分析，确定剪接变体Δ341为神经肽CAPA-PK的特异性受体，并且在激活后，Δ341信号转导至ERK1 / 2途径。进一步的表征表明，Δ341与Gαi/ o偶联，与Gαq偶联的典型CAPA-PVK受体不同，通过Gβγ-PI3K-PKCζ信号级联触发ERK1 / 2磷酸化。此外，我们的ELISA数据表明，由于缺少GRKs介导的磷酸化位点，剪接变体Δ341的配体依赖性内在化显着受损。我们的发现凸显了这种知识在将来对GPCR剪接变体进行分子，药理和生理研究的潜力。