Key interactions by conserved polar amino acids located at the transmembrane helical boundaries in Class B GPCRs modulate activation, effector specificity and biased signalling in the glucagon-like peptide-1 receptor.
Key interactions by conserved polar amino acids located at the transmembrane helical boundaries in Class B GPCRs modulate activation, effector specificity and biased signalling in the glucagon-like peptide-1 receptor.
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DOI：
10.1016/j.bcp.2016.08.015
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发表时间：
2016-10-15
影响因子：
5.8
通讯作者：
Sexton, Patrick M.
中科院分区：
文献类型：
--
作者：
Wootten, Denise;Reynolds, Christopher A.;Smith, Kevin J.;Mobarec, Juan C.;Furness, Sebastian G. B.;Miller, Laurence J.;Christopoulos, Arthur;Sexton, Patrick M.
B 类 GPCR 可以激活多个信号传导效应器，并有可能响应配体刺激而表现出偏向激动作用。之前，我们重点介绍了关键 TM 结构域极性氨基酸，它们对 GLP-1 受体的功能至关重要，而 GLP-1 受体是糖尿病和肥胖症的关键治疗靶点。本研究结合诱变、药理学表征、数学和计算分子模型，鉴定了位于 B 类 GPCR TM 螺旋边界附近的其他高度保守的极性残基，这些残基对于 GLP-1 受体稳定性和/或控制信号特异性和偏向激动非常重要。这包括 (i) 位于 TM 3、4 和 5 细胞外边界的三个带正电荷的残基（R3.30227、K4.64288、R5.40310），分子模型预测这些残基可稳定细胞外环 2，这是配体亲和力和受体激活的关键结构域； (ii) 位于受体细胞质面的 TM 2 (R2.46176)、6 (R6.37348) 和 7 (N7.61406 和 E7.63408) 残基之间的预测氢键网络，对于稳定非活性受体和指导信号特异性非常重要，(iii) TM 5 (R5.56326) 底部的残基和TM6（K6.35346 和 K6.40351）对于受体激活和下游信号传导至关重要； (iv) 预计参与 TM4 稳定的残基（N2.52182 和 Y3.52250）也会影响细胞信号传导。总的来说，这项工作扩展了我们对 GLP-1 受体肽介导的信号传导的理解。
Class B GPCRs can activate multiple signalling effectors with the potential to exhibit biased agonism in response to ligand stimulation. Previously, we highlighted key TM domain polar amino acids that were crucial for the function of the GLP-1 receptor, a key therapeutic target for diabetes and obesity. Using a combination of mutagenesis, pharmacological characterisation, mathematical and computational molecular modelling, this study identifies additional highly conserved polar residues located towards the TM helical boundaries of Class B GPCRs that are important for GLP-1 receptor stability and/or controlling signalling specificity and biased agonism. This includes (i) three positively charged residues (R3.30227, K4.64288, R5.40310) located at the extracellular boundaries of TMs 3, 4 and 5 that are predicted in molecular models to stabilise extracellular loop 2, a crucial domain for ligand affinity and receptor activation; (ii) a predicted hydrogen bond network between residues located in TMs 2 (R2.46176), 6 (R6.37348) and 7 (N7.61406 and E7.63408) at the cytoplasmic face of the receptor that is important for stabilising the inactive receptor and directing signalling specificity, (iii) residues at the bottom of TM 5 (R5.56326) and TM6 (K6.35346 and K6.40351) that are crucial for receptor activation and downstream signalling; (iv) residues predicted to be involved in stabilisation of TM4 (N2.52182 and Y3.52250) that also influence cell signalling. Collectively, this work expands our understanding of peptide-mediated signalling by the GLP-1 receptor.
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