Oka Yuki, Omura Masayo, Kataoka Hiroshi, Touhara Kazushige
Department of Integrated Biosciences, The University of Tokyo, Chiba, Japan.
EMBO J. 2004 Jan 14;23(1):120-6. doi: 10.1038/sj.emboj.7600032. Epub 2003 Dec 18.
The detection of thousands of volatile odorants is mediated by several hundreds of different G protein-coupled olfactory receptors (ORs). The main strategy in encoding odorant identities is a combinatorial receptor code scheme in that different odorants are recognized by different sets of ORs. Despite increasing information on agonist-OR combinations, little is known about the antagonism of ORs in the mammalian olfactory system. Here we show that odorants inhibit odorant responses of OR(s), evidence of antagonism between odorants at the receptor level. The antagonism was demonstrated in a heterologous OR-expression system and in single olfactory neurons that expressed a given OR, and was also visualized at the level of the olfactory epithelium. Dual functions of odorants as an agonist and an antagonist to ORs indicate a new aspect in the receptor code determination for odorant mixtures that often give rise to novel perceptual qualities that are not present in each component. The current study also provides insight into strategies to modulate perceived odorant quality.
数千种挥发性气味分子的检测是由数百种不同的G蛋白偶联嗅觉受体（OR）介导的。编码气味分子特性的主要策略是一种组合受体编码方案，即不同的气味分子由不同的OR组合识别。尽管关于激动剂-OR组合的信息越来越多，但对于哺乳动物嗅觉系统中OR的拮抗作用却知之甚少。在这里，我们表明气味分子会抑制OR的气味反应，这是受体水平上气味分子之间存在拮抗作用的证据。这种拮抗作用在异源OR表达系统和表达特定OR的单个嗅觉神经元中得到了证实，并且在嗅觉上皮水平也可以观察到。气味分子作为OR的激动剂和拮抗剂的双重功能表明，在确定气味混合物的受体编码方面有一个新的方面，气味混合物常常会产生各成分中不存在的新的感知特性。当前的研究还为调节感知到的气味质量的策略提供了见解。
