Ric-8B interacts with Gαolf and Gγ13 and co-localizes with Gαolf, Gβ1 and Gγ13 in the cilia of olfactory sensory neurons

Olfactory sensory neurons are able to detect odorants with high sensitivity and specificity. We have demonstrated that Ric-8B, a guanine nucleotide exchange factor (GEF), interacts with Gαolf and enhances odorant receptor signaling. Here we show that Ric-8B also interacts with Gγ13, a divergent member of the Gγ subunit family which has been implicated in taste signal transduction, and is abundantly expressed in the cilia of olfactory sensory neurons. We show that Gβ1 is the predominant Gβ subunit expressed in the olfactory sensory neurons. Ric-8B and Gβ1, like Gαolf and Gγ13, are enriched in the cilia of olfactory sensory neurons. We also show that Ric-8B interacts with Gαolf in a nucleotide dependent manner, consistent with the role as a GEF. Our results constitute the first example of a GEF protein that interacts with two different olfactory G protein subunits and further implicate Ric-8B as a regulator of odorant signal transduction.