PT - JOURNAL ARTICLE AU - Daria S. Hekmat-Scafe AU - R. Alexander Steinbrecht AU - John R. Carlson TI - Coexpression of Two Odorant-Binding Protein Homologs in<em>Drosophila</em>: Implications for Olfactory Coding AID - 10.1523/JNEUROSCI.17-05-01616.1997 DP - 1997 Mar 01 TA - The Journal of Neuroscience PG - 1616--1624 VI - 17 IP - 5 4099 - http://www.jneurosci.org/content/17/5/1616.short 4100 - http://www.jneurosci.org/content/17/5/1616.full SO - J. Neurosci.1997 Mar 01; 17 AB - Odorant-binding proteins (OBPs) are small soluble proteins present in the aqueous medium surrounding olfactory receptor neurons. Their function in olfaction is still unknown: they have been proposed to facilitate the transit of hydrophobic molecules to olfactory receptors, to deactivate the odorant stimulus, and/or to play a role in chemosensory coding. In this study we examine the genomic organization and expression patterns of twoolfactory-specific genes (OS-E and OS-F) ofDrosophila melanogaster, the products of which are members of a protein family in Drosophila sharing sequence similarity with moth OBPs. We show that theOS-E and OS-F transcription units are located &lt;1 kb apart. They are oriented in the same direction and display a similar intron–exon organization. Expression of both OS-E and OS-F proteins is restricted spatially to the ventrolateral region of the Drosophila antenna. Within this region both OS-E and OS-F proteins are expressed within two different types of sensory hairs: in most, if not all, sensilla trichodea and in ∼40% of the interspersed small sensilla basiconica. We consistently observe that OS-E and OS-F are coexpressed, indicating that an individual sensillum can contain more than one odorant-binding protein. The functional significance of the observed expression pattern and its implications for olfactory coding are discussed.