Title :
Tas1r3 , encoding a new candidate taste
receptor , is allelic to the sweet responsiveness locus Sac
Abstract :
- The ability to taste the sweetness of carbohydrate-rich foodstuffs has a critical role in the nutritional status of humans
- Although several components of bitter transduction pathways have been identified, the receptors and other sweet transduction elements remain unknown
- The Sac locus in mouse, mapped to the distal end of chromosome 4 (refs
- 7-9), is the major determinant of differences between sweet-sensitive and -insensitive strains of mice in their responsiveness to saccharin, sucrose and other sweeteners
- To identify the human Sac locus, we searched for candidate genes within a region of approximately one million base pairs of the sequenced human genome syntenous to the region of Sac in mouse
- From this search, we identified a likely candidate: T1R3 , a previously unknown G protein-coupled receptor ( GPCR ) and the only GPCR in this region
- Mouse Tas1r3 (encoding T1r3 ) maps to within 20,000 bp of the marker closest to Sac (ref
- 9) and, like human TAS1R3 , is expressed selectively in taste receptor cells
- By comparing the sequence of Tas1r3 from several independently derived strains of mice, we identified a specific polymorphism that assorts between taster and non-taster strains
- According to models of its structure, T1r3 from non-tasters is predicted to have an extra amino-terminal glycosylation site that, if used, would interfere with dimerization