Fig 2. Capacity of three cell lines as a functional expression cell system for ORs.

A total of 412 ORs were expressed in different cell lines. Each OR was co-transfected with CRE/luc2PpGL4.29, pRL-CMV, and RTP1S in HEK293 cells whereas Gαolf was also co-transfected in the other three cell lines. They were stimulated with a mixture of six odorants in the growth medium without FBS. The X-axis lists each of the 412 ORs, and color bars represent OR families. Y-axis indicates the response of cells expressing each OR as a fold increase. Data are presented as the mean values from two screening replicates. The dashed line denotes mean + 2SD of all the examined ORs except for those validated in HEK293 cells. The name of the receptor is described if the response value in the follow-up dose-response analysis meets our criteria (S3–S6 Figs).