Coexpression of two odorant-binding protein homologs in Drosophila: implications for olfactory coding.
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 two olfactory-specific genes (OS-E and OS-F) of Drosophila melanogaster, the products of which are members of a protein family in Drosophila sharing sequence similarity with moth OBPs. We show that the OS-E and OS-F transcription units are located <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 approximately 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.
Hekmat-Scafe
D S
DS
Department of Biology, Yale University, New Haven, Connecticut 06520-8103, USA.
Steinbrecht
R A
RA
Carlson
J R
JR
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000378:metabolism*; D005786:Gene Expression Regulation; D017344:Genes, Insect; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012679:Sense Organs / Q000378:metabolism; D012903:Smell / Q000235:genetics / Q000502:physiology*
D002352:Carrier Proteins; D029721:Drosophila Proteins; C087695:Obp83a protein, Drosophila; C087694:Obp83b protein, Drosophila; D011993:Recombinant Fusion Proteins