New GPCRs from a human lingual cDNA library.

Sweet and bitter taste perception involve G protein coupled receptors (GPCRs) present at the taste receptor cell surface. It is likely that various mechanisms are active and various families of GPCRs are involved in the perception of these tastes. The expression of GPCRs in human tongue was studied using degenerated primers corresponding to transmembrane domains 2 or 3 (for 5' primer), 6 or 7 (for 3' primer) of olfactory-like receptors in reverse transcription-polymerase chain reaction experiments. It was demonstrated that four previously identified, eight new olfactory-like receptor genes, three previously known and eight new olfactory-like receptor pseudogenes, mostly located on chromosome 11, are expressed in adult tongue and/or in fetal tongue. Previously identified genes include HGMP071, HTPCR06, TPCR120 and TPCR85 whose cDNAs were originally isolated from male germinal cells. New genes were named JCG1, JCG2, JCG3, JCG4, JCG5, JCG6, JCG9 and JCG10. HGMP071, HTPCR06, TPCR120, JCG3 and JCG5 are also expressed in the epithelium of adult tongue, whereas all these genes are expressed in fetal tongue. Although functional studies are needed before definitive conclusions are made, the obtained results imply that lingual olfactory-like receptors could be involved in taste perception.