G qα subunit mediates receptor site-specific adaptation in the sugar taste receptor cell of the blowfly, Phormia regina

Abstract

Listen

Translate article

The gustatory system is essential for almost all animals. The recent identification of G protein-coupled receptor proteins (GPCRs) has progressed molecular biological studies of gustatory systems, although the signal transduction mechanisms have not yet been fully elucidated. In vision and olfactory receptor cells, G q class G protein is known to be a major signal transducer. By functional blocking of intrinsic G q with an anti-G q/11α antibody, we investigated the roles of G q in the sugar receptor cell of the blowfly, Phormia regina. Before and after introduction of the anti-G q/11α antibody into the cell through the DOC-permeabilized cell membrane, we recorded the responses of the receptor cell to sucrose and d-fructose, which stimulate different receptor sites, respectively. The initial impulse frequency in response to either sucrose or d-fructose was not changed by antibody introduction, whereas the adaptation rate in sucrose stimulation, but not fructose stimulation, became slower after antibody introduction. These results indicate that: (1) G q is a regulator of adaptation in the sugar receptor cell of Phormia, rather than a transducer, and (2) different adaptation mechanisms are promoted by stimulations with sucrose and d-fructose.