Dhallan R S, Yau K W, Schrader K A, Reed R R
Department of Biomedical Engineering, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Nature. 1990 Sep 13;347(6289):184-7. doi: 10.1038/347184a0.
Odorant signal transduction occurs in the specialized cilia of the olfactory sensory neurons. Considerable biochemical evidence now indicates that this process could be mediated by a G protein-coupled cascade using cyclic AMP as an intracellular second messenger. A stimulatory G protein alpha subunit is expressed at high levels in olfactory neurons and is specifically enriched in the cilia, as is a novel form of adenylyl cyclase. This implies that the olfactory transduction cascade might involve unique molecular components. Electrophysiological studies have identified a cyclic nucleotide-activated ion channel in olfactory cilia. These observations provide evidence for a model in which odorants increase intracellular cAMP concentration, which in turn activates this channel and depolarizes the sensory neuron. An analogous cascade regulating a cGMP-gated channel mediates visual transduction in photoreceptor cells. The formal similarities between olfactory and visual transduction suggest that the two systems might use homologous channels. Here we report the molecular cloning, functional expression and characterization of a channel that is likely to mediate olfactory transduction.
气味信号转导发生在嗅觉感觉神经元的特化纤毛中。现在大量的生化证据表明，这个过程可能由一个以环磷酸腺苷（cAMP）作为细胞内第二信使的G蛋白偶联级联反应介导。一种刺激性G蛋白α亚基在嗅觉神经元中高水平表达，并且像一种新型腺苷酸环化酶一样，在纤毛中特别富集。这意味着嗅觉转导级联反应可能涉及独特的分子成分。电生理学研究已经在嗅觉纤毛中鉴定出一种环核苷酸激活的离子通道。这些观察结果为一种模型提供了证据，即气味剂增加细胞内cAMP浓度，进而激活该通道并使感觉神经元去极化。一种调节cGMP门控通道的类似级联反应介导光感受器细胞中的视觉转导。嗅觉和视觉转导之间的形式相似性表明，这两个系统可能使用同源通道。在此我们报告一种可能介导嗅觉转导的通道分子克隆、功能表达及特性。
