アブストラクト(15巻1号:The Bulletin of Kanagawa Dental College)

The Bulletin of Kanagawa Dental College

English

Title : Receptor Proteins in Olfaction
Subtitle : GUEST ARTICLE
Authors : Steven Price
Authors(kana) :
Organization : Physiology, Medical College of Virginia, Virginia Commonwealth University, Sensory Physiology and Perception Program, National Science Foundation
Journal : The Bulletin of Kanagawa Dental College
Volume : 15
Number : 1
Page : 5-8
Year/Month : 1987 / 3
Article : Report
Publisher : Kanagawa Odontological Society
Abstract : [Summary and Conclusions] Two proteins have been isolated from the olfactory epithelium of dogs. They are poorly extractable in the absence of detergents but are extracted readily when a detergent is present. Therefore, they are probably constituents of some membranous component of the cells. They are not found in respiratory epithelium adjacent to the tissue in which they occur. Therefore, they are not general constituents of cells, cilia or mucus. One has a high affinity for compounds related to anisole and the other for compounds related to benzaldehyde. Their mobilities on polyacrylamide gel electrophoresis are identical, although they are different molecules. Antisera raised in rabbits against each, when applied to the olfactory mucosa of mice, inhibit the electrophysiological responses to odorants. These properties strongly suggest that the proteins are part of the olfactory transduction chain, probably actual receptor proteins. It was hypothesized that olfactory receptor proteins comprise a class of structurally related molecules. This is consistent with the fact that antisera raised against either protein inhibit olfactory responses to odorants other than those to which the proteins bind. Affinity columns prepared from immunoglobulins against the anisole binding protein bound much more protein from dog olfactory epithelial extracts than could be accounted for as anisole binding protein, in accord with the hypothesis. Monoclonal antibodies were raised against the two proteins. Of 26 such antibodies, about 12% were specific inhibitors of responses to the odorant to which the protein bound. These probably bind directly to the region of the protein with which the odorant interacts. Another 35% are general inhibitors of olfactory responses. These probably bind to the region of the protein that is common to all olfactory receptor proteins. The remaining 54% do not inhibit olfactory responses. These probably bind to the part of the protein that is buried in the membrane and is inaccessible to the antibodies in living cells. The data are completely consistent with the hypothesis that there is a structurally related class of olfactory receptor proteins of which the anisole and benzaldehyde binding proteins are both examples. Finally, there is the question of whether interaction of receptor proteins is the sole mechanism for stimulation of olfactory receptor cells. None of the monoclonal antibodies raised against anisole or benzaldehyde binding proteins inhibits the EOG by as much as 40%. Thus, at least half of the response is probably initiated by mechanisms other than mediation by receptor proteins. Those mechanisms probably include the so-called nonspecific effects of the odorant chemicals on cells. If this is correct, then the mechanisms can be expected to differ for different odorants and odorant concentrations. The question, "What is the mechanism of stimulation of olfactory receptor cells?" may not have a general answer that is universally applicable. The hypothesis that the sole or main route for stimulation is via receptor proteins is intellectually attractive in its simplicity, but nature may not be as attracted to simplicity as we are.
Practice : Dentistry
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