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Biochemistry

Title:		"Molecular and functional characterization of an odorant binding protein of the Asian elephant, Elephas maximus: implications for the role of lipocalins in mammalian olfaction"
Author(s):		Lazar J; Greenwood DR; Rasmussen LE; Prestwich GD;
Address:		"Department of Medicinal Chemistry, The University of Utah, 419 Wakara Way, Suite 205, Salt Lake City, UT 84108-1257, USA"
Journal Title:		Biochemistry
Year:		2002
Volume:		41
Issue:		39
Page Number:		11786 - 11794
DOI:		10.1021/bi0256734
ISSN/ISBN:		0006-2960 (Print) 0006-2960 (Linking)
Abstract:		"The sex pheromone present in the pre-ovulatory urine of female Asian elephants is the simple lipid (Z)-7-dodecen-1-yl acetate (Z7-12:Ac). Using radiolabeled probes, we have identified a pheromone binding protein that is abundant in the mucus of the trunk; this protein is homologous to a class of lipocalins known as odorant binding proteins (OBPs). To test five previously proposed roles for the OBP in chemosensory perception, we determined the equilibrium dissociation constant of the OBP-pheromone complex, as well as the association and dissociation rates. Using a mathematical model in conjunction with experimental data, we suggest that the binding and release of the pheromone by the OBP are too slow for the OBP to function in transporting the pheromone through the mucus that covers the olfactory sensory epithelium. Our data indicate that the elephant OBP only modestly increases the solubility of the pheromone in the mucus. Our results are most consistent with the notion that elephant OBP functions as a scavenger of the pheromone and possibly other ligands, including odorants. In light of these findings, and published results for other mammalian OBP-ligand complexes, a general model for the role of OBPs in mammalian olfaction is proposed. Moreover, the potential implications of these findings for interaction of Z7-12:Ac with insect antennal proteins are discussed"
Keywords:		Amino Acid Sequence Animals Cattle Cricetinae Elephants/*metabolism Female Half-Life Kinetics Male Mice Molecular Sequence Data Mucoproteins/chemistry/metabolism/physiology Mucus/chemistry/metabolism/physiology *Odorants Olfactory Mucosa/chemistry/metabol;
Notes:		"MedlineLazar, Josef Greenwood, David R Rasmussen, L E L Prestwich, Glenn D eng DC 03320/DC/NIDCD NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 2002/09/25 Biochemistry. 2002 Oct 1; 41(39):11786-94. doi: 10.1021/bi0256734"