Young Janet M, Trask Barbara J
Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N., C3-168, PO Box 19024, Seattle, Washington 98109, USA.
Hum Mol Genet. 2002 May 15;11(10):1153-60. doi: 10.1093/hmg/11.10.1153.
Olfactory receptor (OR) proteins interact with odorant molecules in the nose, initiating a neuronal response that triggers the perception of a smell. The OR family is one of the largest known mammalian gene families, with around 900 genes in human and 1500 in mouse. After discounting pseudogenes, the functional repertoire in mouse is more than three times larger than that of human. OR genes encode G-protein-coupled receptors containing seven transmembrane domains. ORs are arranged in clusters of up to 100 genes dispersed in 40-100 genomic locations. Each neuron in the olfactory epithelium expresses only one allele of one OR gene. The mechanism of gene choice is still unknown, but must involve locus, gene, and allele selection. The gene family has expanded mainly by tandem duplications, many of which have occurred since the divergence of the rodent and primate lineages. Interchromosomal segmental duplications including OR genes have also occurred, but more commonly in the human than the mouse family. As a result, many human OR genes have several possible mouse orthologs, and vice versa. Sequence and copy number polymorphisms in OR genes have been described, which may account for interindividual differences in odorant detection thresholds.
嗅觉受体（OR）蛋白在鼻腔中与气味分子相互作用，引发神经元反应，从而触发嗅觉感知。OR家族是已知的最大的哺乳动物基因家族之一，人类约有900个基因，小鼠有1500个基因。去除假基因后，小鼠的功能基因库比人类的大三倍多。OR基因编码含有七个跨膜结构域的G蛋白偶联受体。OR基因以多达100个基因的簇形式排列，分散在40 - 100个基因组位置。嗅觉上皮中的每个神经元仅表达一个OR基因的一个等位基因。基因选择机制仍然未知，但肯定涉及基因座、基因和等位基因的选择。该基因家族主要通过串联重复进行扩增，其中许多重复发生在啮齿动物和灵长类谱系分化之后。包括OR基因在内的染色体间片段重复也有发生，但在人类家族中比在小鼠家族中更常见。因此，许多人类OR基因有几个可能的小鼠直系同源基因，反之亦然。已经描述了OR基因中的序列和拷贝数多态性，这可能解释了个体间气味检测阈值的差异。
