Dual signal transduction mediated by a single type of olfactory receptor expressed in a heterologous system

Jin Ko Hwi, Hyun Park Tai

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Controversy exists over the relationship between the cAMP and IP 3 pathways in vertebrate olfactory signal transduction, as this process is known to occur by either of the two pathways. Recent studies have shown that a single olfactory neuron responds to both cAMP- and IP 3-producing odorants, suggesting the existence of an olfactory receptor protein that can recognize both ligands. In this study we found that the rat olfactory receptor I7, stably expressed in HEK-293 cells, triggers the cAMP pathway upon stimulation by a specific odorant (octanal) at concentrations lower than 10-4 M; however, the receptor triggers both pathways at higher concentrations. This indicates that a single olfactory receptor, stimulated by a single pathway-inducing odorant, can evoke both pathways at high odorant concentrations. Using this heterologous system, both the dose-dependent response and receptor I7 specificity were analyzed. The dose-dependent Ca 2+ response curve, which also includes the release of Ca2+ ions from internal stores at high odorant concentrations, was not monotonous, but had a local maximum and minimum with 10-10 and 10-7 M octanal, respectively, and reached a plateau at 10-2 M octanal. The specificity of the I7 receptor was lower when exposed to higher concentrations of odorants.

Original languageEnglish
Pages (from-to)59-68
Number of pages10
JournalBiological Chemistry
Issue number1
StatePublished - Jan 2006

Bibliographical note

Funding Information:
This work was supported by the Korea Science & Engineering Foundation through the Nano-Bioelectronics and Systems Research Center, Seoul National University, Seoul, Korea. We thank Randall R. Reed (Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, USA) for the rho-tag gene, Akihito Yasuoka (Bio-oriented Technology Research Advancement Institution, Saitama, Japan) for pVL-I7, and Paul A. Hargrave (J. Hillis Miller Health Center, Department of Ophthalmology, University of Florida College of Medicine, Gainesville, FL, USA) for the B6-30 cell line.


  • HEK-293
  • IP pathway
  • Odorant
  • Olfactory receptor I7
  • Signal transduction
  • cAMP pathway


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