Ligand screening of THTR G protein-coupled receptors using receptor-Galpha16 fusion proteins

Abstract

Background: Computer searches for human genome revealed a family of novel G-protein coupled receptors, THTRs, which are highly homologous to a family of bitter taste receptors, T2Rs (Takeda et al. (2002) FEBS Lett. 520, 97). We have previously cloned all human THTR and T2R genes. We have also shown that the assay system using receptor-Gα16 fusion proteins is an effective method for ligand screening. In this study, this assay system was utilized to identify ligands of THTRs and T2Rs. Method: THTR- and T2R-Gα16 fusion protein cDNA were constructed and stably expressed in CHO cells. The cells were stimulated with various stimulants, including tastants. Subsequently, The supernatant of the cells was collected and prostaglandin E₂ generation was measured using an enzyme immunoassay kit. Tissue distribution of receptors was investigated by RT-PCR. Results & Conclusion: THTR 5 was highly expressed in tongue epithelia. In cells, expressing THTR5-Gα16 fusion protein, glucose induced marked prostaglandin E₂ generation. These data suggested that THTR5 might function as glucose receptor in tongue epithelia. [Jpn J Physiol 54 Suppl:S129 (2004)]