Expression of olfactory receptor protein in e.coli and its application to olfactory biosensor

Abstract

An olfactory receptor protein is a 7-transmembrane protein that is expressed at the surface of olfactory sensory neuron. It is known to bind to odorant molecules and constitute the first step in sense of smell. Since the discovery of olfactory receptor gene in 1991, it is now known that there are as many as 1000 genes for olfactory receptors in the mammalian genome, probably being the largest gene family of GPCR(G-protein coupled receptor). Since thousands of odorant molecules are detected by about 1000 olfactory receptors, there have been some research interests on how such a large number of odors can be detected by a limited number of olfactory receptors. Also, the olfactory system and olfactory receptors are excellent models for structure-function studies, and there have been studies on identification of odorant ligands for several olfactory receptors. But these studies have not shown much progress, due to the difficulty of expressing olfactory receptors in heterologous systems. In our studies, olfactory receptor protein ODR-10 was expressed in E. coli as fusion protein with GST and 6XHis Tag. GST(glutathione Stransferase) and 6XHis genes were fused to 5 and 3 end of odr-10 gene, respectively. Expression of the target protein was checked by SDS-PAGE and western blot, and it was shown that the protein was expressed at the membrane fraction of the host cells, although the expression level was very low...