The highly potent bell pepper odorant 2-isobutyl-3-[3H]methoxypyrazine ([3H]IBMP) binds specifically and saturably to bovine and rat nasal epithelium. Specific binding is not detected in 11 other tissues assayed, and in the rat binding is 9 times higher in olfactory than in respiratory epithelium. We have purified to apparent homogeneity a soluble pyrazine odorant binding protein that constitutes ~1% of the total soluble protein in bovine nasal epithelium. Polyacrylamide gel electrophoresis shows a single band of 19,000 Da and gel filtration data suggest that the native protein is a dimer of 38,000 Da. Binding of [3H]IBMP to the purified protein reveals two binding sites (K(d) = 10 x 10-9 M, B(max) = 135 pmol per mg of protein; K(d) = 3 x 10-6 M, B(max) = 25 nmol per mg of protein). The binding affinities of a homologous series of pyrazine odorants correlate with the human odor detection thresholds of these compounds. This correlation, together with the regional distribution of the protein, suggests that the protein is a physiologically relevant olfactory receptor.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 1985|
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