Amino acids involved in conformational dynamics and G protein coupling of an odorant receptor: targeting gain-of-function mutation
Amino acids involved in conformational dynamics and G protein coupling of an odorant receptor: targeting gain-of-function mutation
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DOI：
10.1111/j.1471-4159.2008.05693.x
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发表时间：
2008-12-01
影响因子：
4.7
通讯作者：
Touhara, Kazushige
中科院分区：
文献类型：
--
作者：
Kato, Aya;Katada, Sayako;Touhara, Kazushige
鸟嘌呤核苷酸结合蛋白（G蛋白）偶联的七种跨膜受体家族中的气味受体（ORs）可以识别和区分数千种不同的气味。气味结合的ORs刺激gs型G蛋白G α olf，从而激活camp介导的嗅觉感觉神经元信号通路。为了更好地了解OR激活和G蛋白偶联的分子基础，我们分析了小鼠ORs的一系列位点定向突变对功能的影响。胞内环或c端保守氨基酸残基的突变导致活性丧失，但不损害配体结合活性，表明这些残基参与了G α s/olf偶联。此外，KAFSTC中or特异性序列基序丝氨酸的突变导致气味反应性急剧增加，这表明该基序参与了调节G蛋白偶联效率的受体构象变化。我们的研究结果提供了ORs如何从非活性状态切换到活性状态，以及激活的ORs如何与G蛋白相互作用的位置和方式。
Thousands of different odorants are recognized and discriminated by odorant receptors (ORs) in the guanine nucleotide-binding protein (G protein)-coupled seven-transmembrane receptor family. Odorant-bound ORs stimulate Gs-type G proteins, G alpha olf, which in turn activates cAMP-mediated signaling pathway in olfactory sensory neurons. To better understand the molecular basis for OR activation and G protein coupling, we analyzed the effects of a series of site-directed mutations of mouse ORs, on function. Mutations of conserved amino acid residues in an intracellular loop or the C-terminus resulted in loss of activity without impairing ligand-binding activity, indicating that these residues are involved in G alpha s/olf coupling. Moreover, mutation of the serine in KAFSTC, the OR-specific sequence motif, resulted in a dramatic increase in odorant responsiveness, suggesting that the motif is involved in a conformational change of the receptor that regulates G protein coupling efficiency. Our results provide insights into how ORs switch from an inactive to an active state, as well as where and how activated ORs interact with G proteins.