G olf : an Olfactory Neuron Specific-G Protein Involved in Odorant Signal Transduction

Abstract

Biochemical and electrophysiological studies suggest that odorants induce responses in olfactory sensory neurons via an adenylate cyclase cascade mediated by a G protein. An olfactory-specific guanosine triphosphate (GTP)-binding protein α subunit has now been characterized and evidence is presented suggesting that this G protein, termed G olf , mediates olfaction. Messenger RNA that encodes G olfα is expressed in olfactory neuroephithelium but not in six other tissues tested. Moreover, within the olfactory epithelium, G olfα appears to be expressed only by the sensory neurons. Specific antisera were used to localize G olfα protein to the sensory apparatus of the receptor neurons. G olfα shares extensive amino acid identity (88 percent) with the stimulatory G protein, G sα . The expression of G olfα in S49 cyc - kin - cells, a line deficient in endogenous stimulatory G proteins, demonstrates its capacity to stimulate adenylate cyclase in a heterologous system.