近年发现多种氨基酰tRNA合成酶具有不同信号调控作用。本研究前期发现牛乳腺上皮细胞（BMEC）中甘氨酰tRNA合成酶（GlyRS）应答氨基酸信号，通过磷酸化、分子剪切和细胞核定位机制激活mTOR信号途径分子的基因转录。本研究拟阐明BMEC中氨基酸激活GlyRS发生磷酸化的信号转导途径。依据前期鉴定的GlyRS细胞浆相互作用蛋白质组，利用体外激酶活性检测及基因功能研究等方法鉴定介导氨基酸信号的GlyRS上游激酶1-2个，揭示氨基酸通过G蛋白偶联受体（GPCRs）及其下游cdc42/Rac/Rho和/或PI3K-PIP3-PDK1信号通路激活GlyRS上游激酶的信号转导机制，及氨基酸转运体对氨基酸作用于GPCRs途径的影响。基于以上结果，进一步利用基因功能和转录调控研究方法揭示氨基酸通过GCN2/eIF2α途径调节GlyRS上游信号途径分子基因表达的机制，以及氨基酸激活GlyRS的正反馈机制。

Aminoacyl tRNA synthetases have been recently discovered to play diverse signaling roles beyond aminoacylation function. We have previously revealed that glycyl tRNA synthetase (GlyRS) is associated with milk protein synthesis and proliferation in bovine mammary epithelial cell (BMEC). GlyRS undergoes phosphorylation, proteolysis, and nuclear localization to activate gene transcription of mTOR signaling molecules in amino acid sensing. In this research, we aim to reveal the signaling transduction pathway through which amino acids trigger the phosphorylation of GlyRS in BMEC. Based on our previously identified the protein interactome of GlyRS in cytoplasm, herein, we first use in vitro kinase activity assay, in conjunction with gene overexpression and knock down approaches, to identify 1-2 of the upstream kinases of GlyRS in amino acid sensing, to unveil the role of G-protein coupled receptors (GPCRs) and their downstream cdc42/Rac/Rho and/or PI3K-PIP3-PDK1 signaling pathways in activating the upstream kinases of GlyRS in amino acid sensing, and the effects of amino acid transporter on the activation of GPCRs signaling. And based on these results, we further want to use gene function study and transcriptional regulation approaches, to reveal the mediation of GCN2/eIF2α signaling transduction pathway in the regulation of transcription of the upstream signaling molecules of GlyRS in amino acid sensing, furthermore to reveal the positive feedback mechanism by which amino acids trigger GlyRS phosphorylation.