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Genetics. 2019 Sep 6. pii: genetics.302629.2019. doi: 10.1534/genetics.119.302629. [Epub ahead of print]

Odor-Specific Deactivation Defects in a Drosophila Odorant Binding Protein Mutant.

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University of Texas Southwestern Medical Center.
University of Texas Southwestern Medical Center


Insect odorant binding proteins are a large, diverse group of low molecular weight proteins secreted into the fluid bathing olfactory and gustatory neuron dendrites. The best-characterized OBP, LUSH (OBP76a) enhances pheromone sensitivity enabling detection of physiological levels of the male-specific pheromone, 11-cis vaccenyl acetate. The role of the other OBPs encoded in the Drosophila genome is largely unknown. Here, using CRISPR-Cas9 we generated and characterized the loss of function phenotype for two genes encoding homologous OBPs, OS-E (OBP83b) and OS-F (OBP83a). Instead of activation defects, these extracellular proteins are required for normal deactivation of odorant responses to a subset of odorants. Remarkably, odorants detected by the same odorant receptor are differentially affected by the loss of the OBPs, revealing an odorant-specific role in deactivation kinetics. In stark contrast to lush mutants, the OS-E/F mutants have normal activation kinetics to the affected odorants, even at low stimulus concentrations, suggesting these OBPs are not competing for these ligands with the odorant receptors. We also show that OS-E and OS-F are functionally redundant as either is sufficient to revert the mutant phenotype in transgenic rescue experiments. These findings expand our understanding of the roles of OBPs to include deactivation of odorant responses.


olfaction; olfactory; perireceptor

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