Molecular cloning and characterization of a lobster Gα(s) protein expressed in neurons of olfactory organ and brain

We have isolated from an American lobster (Homarus americanus) olfactory organ cDNA library a clone, lobGα(s), with >70% identity to mammalian and arthropod Gα(s) sequences. In genomic Southern blots, a fragment of lobGα(s) detected only one band, suggesting the lobsters have a single Gα(s) gene. In brain and olfactory organ, lobGα(s) mRNA was expressed predominantly in neurons, including many of the neuronal cell body clusters of the brain. Gα(s) protein was also expressed broadly, appearing on western blots as a band of 51.8 kDa in brain, eyestalk, pereiopod, dactyl, tail muscle, olfactory organ, and aesthetasc hairs. These results suggest that lobGα(s) plays a role in a wide variety of signal transduction events. Its presence in the olfactory aesthetasc hairs, which are almost pure preparations of the outer dendrites of the olfactory receptor neurons, and the expression of lobGα(s) mRNA in the olfactory receptor neurons of the olfactory organ indicate that lobGα(s) may mediate olfactory transduction. That virtually all ORNs express lobGα(s) mRNA equally predicts that hyperpolarizing odor responses mediated by cyclic AMP are a property of all lobster olfactory receptor neurons.