Gα14 is a candidate mediator of sweet/umami signal transduction in the posterior region of the mouse tongue

Gustducin, a Gα subunit expressed in taste cells, is known as a key molecule for sweet, umami and bitter taste signal transduction. However, previous studies demonstrated that the contribution of gustducin to the sweet/umami responses in the posterior region of the tongue is less than that in the anterior region, implying the existence of another Gα subunit mediating sweet/umami taste signal transduction. Here, we propose Gα14, a member of Gαq family, as the candidate mediator. Gα14 was found in our subtracted full-length cDNA library derived from mouse circumvallate papillae (CV) and expressed in a subset of taste cells in CV and foliate papillae, but not in fungiform papillae and soft palate. Gα14 was co-expressed with T1r3, a sweet/umami taste receptor, but not with gustducin in CV. These results suggest the important roles of Gα14 in sweet/umami taste signal transduction in the posterior region of the tongue.