G protein-coupled receptors (GPCRs) serve as critical communication hubs, translating a wide range of extracellular signals into intracellular responses that govern numerous physiological processes. In class-A GPCRs, conserved motifs mediate conformational changes of the active states of the receptor, and signal transduction is achieved by selectively binding to Gα proteins and/or adapter protein, arrestin. Apelin receptor (APJR) is a class-A GPCR that regulates a wide range of intracellular signalling cascades in response to apelin and elabela peptide ligands. Understanding how conserved motifs within APJR mediate activation and signal specificity remains unexplored. This study focuses on the functional roles of the DRY and NPxxY motifs within APJR by analyzing their impact on downstream signaling pathways across the receptor's conformational ensembles. Our findings provide compelling evidence that mutations within the conserved DRY and NPxxY motifs of APJR significantly alter its conformational preferences where modification of DRY motif leads to abrogation of G-protein coupling and mutation of NPxxY motif causing abolition of β-arrestin-2 recruitment. These observations shed light on the importance of these motifs in APJR activation and its potential for functional selectivity, highlighting the role of DRY/NPxxY as conformational switches of APJR signalling.

中文翻译：

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DRY 和 NPxxY 基序在 apelin 受体选择性激活下游信号传导中的作用不同。


G 蛋白偶联受体 （GPCR） 作为关键的通信枢纽，将广泛的细胞外信号转化为控制许多生理过程的细胞内反应。在 A 类 GPCR 中，保守基序介导受体活性状态的构象变化，并通过选择性结合 Gα 蛋白和/或衔接蛋白 arrestin 来实现信号转导。Apelin 受体 （APJR） 是一种 A 类 GPCR，可响应 apelin 和 elabela 肽配体调节广泛的细胞内信号级联反应。了解 APJR 中的保守基序如何介导激活和信号特异性仍有待探索。本研究通过分析它们对受体构象集合中下游信号通路的影响，重点关注 DRY 和 NPxxY 基序在 APJR 中的功能作用。我们的研究结果提供了令人信服的证据，表明 APJR 保守的 DRY 和 NPxxY 基序内的突变显着改变了其构象偏好，其中 DRY 基序的修饰导致 G 蛋白偶联的废除，NPxxY 基序的突变导致 β-arrestin-2 募集的消除。这些观察结果阐明了这些基序在 APJR 激活中的重要性及其功能选择性的潜力，突出了 DRY/NPxxY 作为 APJR 信号传导构象开关的作用。