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Chem Senses

Title:		Perireceptor and receptor events in olfaction. Comparison of concentration and flux detectors: a modeling study
Author(s):		Rospars JP; Krivan V; Lansky P;
Address:		"Unite de Biometrie, INRA, 78026 Versailles Cedex, France"
Journal Title:		Chem Senses
Year:		2000
Volume:		25
Issue:		3
Page Number:		293 - 311
DOI:		10.1093/chemse/25.3.293
ISSN/ISBN:		0379-864X (Print) 0379-864X (Linking)
Abstract:		"Transduction in chemosensory cells begins with the association of ligand molecules to receptor proteins borne by the cell membrane. The receptor-ligand complexes formed act as signaling compounds that trigger a G-protein cascade. This receptor-ligand interaction, described here by a single-step or double-step reaction, depends on factors controlling the access of the ligand molecules to the cell membrane. Two basic mechanisms can be distinguished: concentration detectors (CD), in which the ligand can freely diffuse to the membrane, and flux detectors (FD), in which it accumulates irreversibly in a distinct perireceptor space where it is chemically deactivated. These two systems, plus their generalization, are investigated and compared. The transient and steady-state numbers of complexes are studied as a function of the external ligand concentration. The biological significance of the results is shown in a well-studied example of FD, the insect sex-pheromone olfactory receptor neuron. How the number of complexes can code for the intensity of stimulation is analyzed using the size, dynamic range and sensitivity of the steady-state responses, and the time needed to reach a predefined level of the transient responses. It is shown that the FD design affords a large increase in sensitivity (a shift of the threshold response towards low concentration) with respect to the CD design, which is paid for by a lesser ability to follow fast changes in stimulus intensity"
Keywords:		"Kinetics *Models, Biological Odorants Olfactory Pathways/*physiology Smell/*physiology;"
Notes:		"MedlineRospars, J P Krivan, V Lansky, P eng Comparative Study Research Support, Non-U.S. Gov't England 2000/06/27 Chem Senses. 2000 Jun; 25(3):293-311. doi: 10.1093/chemse/25.3.293"