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Updated: Sep 2, 2025

High-throughput Analysis of Mammalian Olfactory Receptors: Measurement of Receptor Activation via Luciferase Activity
Published on: June 2, 2014
Low signaling efficiency from receptor to effector in olfactory transduction: A quantified ligand-triggered GPCR
Rong-Chang Li1, Laurie L Molday2, Chih-Chun Lin1,3
1Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
None:
G protein-coupled receptor (GPCR) signaling is ubiquitous. As an archetype of this signaling motif, rod phototransduction has provided many fundamental, quantitative details, including a dogma that one active GPCR molecule activates a substantial number of downstream G protein/enzyme effector complexes. However, rod phototransduction is light-activated, whereas GPCR pathways are predominantly ligand-activated. Here, we report a detailed study of the ligand-triggered GPCR pathway in mammalian olfactory transduction, finding that an odorant-receptor molecule when (one-time) complexed with its most effective odorants produces on average much less than one downstream effector. Further experiments gave a nominal success probability of tentatively ∼10-4 (more conservatively, ∼10-2 to ∼10-5). This picture is potentially more generally representative of GPCR signaling than is rod phototransduction, constituting a paradigm shift.
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