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1: Science. 2005 Jun 24;308(5730):1931-4.
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Elementary response of olfactory receptor neurons to odorants.

Bhandawat V, Reisert J, Yau KW.

Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. vbhanda@mail.jhmi.edu

Signaling by heterotrimeric GTP-binding proteins (G proteins) drives numerous cellular processes. The number of G protein molecules activated by a single membrane receptor is a determinant of signal amplification, although in most cases this parameter remains unknown. In retinal rod photoreceptors, a long-lived photoisomerized rhodopsin molecule activates many G protein molecules (transducins), yielding substantial amplification and a large elementary (single-photon) response, before rhodopsin activity is terminated. Here we report that the elementary response in olfactory transduction is extremely small. A ligand-bound odorant receptor has a low probability of activating even one G protein molecule because the odorant dwell-time is very brief. Thus, signal amplification in olfactory transduction appears fundamentally different from that of phototransduction.

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PMID: 15976304 [PubMed - indexed for MEDLINE]