Sense of Smell
Published Online: 15 SEP 2006
Copyright © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved.
Reviews in Cell Biology and Molecular Medicine
How to Cite
Lane, R. P., Smutzer, G. S., Smutzer, G. S. and Doty, R. L. 2006. Sense of Smell. Reviews in Cell Biology and Molecular Medicine. .
- Published Online: 15 SEP 2006
Olfactory receptor genes devoted to the sense of smell compose the largest multigene family in mammalian genomes. Although the number of receptor genes and related olfactory-specific genes vary in different species, up to 1% of the mammalian genome may be devoted exclusively to the sense of smell. This number reflects the importance of olfaction throughout vertebrate evolution, and the role of olfaction in maintaining a wide range of life-supporting activities, including feeding, nutrition, enhancement of gustatory responses, safety, predator/prey detection, and esthetics. In humans, ∼400 different genes encode functional olfactory receptor proteins that localize to the ciliary membranes of ∼6 000 000 receptor cells in the olfactory neuroepithelium only the visual system of vertebrates prossesses with more receptor cells.
In this chapter, we review basic aspects of olfactory system anatomy, expression of odorant receptors within sensory neurons, and pathways of mammalian and invertebrate olfactory transduction. We focus primarily on the main (i.e. nonvomeronasal organ) olfactory system of vertebrates. In particular, specific attention is paid to the (1) chromosomal organization of olfactory receptor genes; (2) monogenic expression of olfactory receptor genes; (3) regulation of odorant receptor gene transcription within sensory neurons; (4) role of olfactory receptor gene expression in regulating the projection of functionally distinct olfactory sensory neurons from the olfactory epithelium to the olfactory bulb; (5) initial biochemical transduction events that include the molecular mechanisms responsible for stimulus transduction and generation of second messengers for signal amplification; and (6) microanatomy and function of olfactory bulb circuits. The plasticity of the olfactory system, as reflected by neurogenesis both within the olfactory neuroepithelium and the olfactory bulb is discussed in detail, as are a number of inherited and idiopathic human disorders associated with olfactory dysfunction in humans.
- Gene Repertoire;
- Odor Coding;
- Second Messenger;