High-resolution genetic mapping of the saccharin preference locus (Sac) and the putative sweet taste receptor (T1R1) gene (Gpr70) to mouse distal Chromosome 4

The Sac (saccharin preference) locus affecting mouse behavioral and neural responsiveness to sweeteners has been mapped to distal Chr 4. A putative sw eet taste receptor, T1R1, has been recently cloned, and the gene encoding i t, Gpr70, has also been mapped to mouse distal Chr 4. To assess Gpr70 as a candidate gene for Snc, we compared the Gpr70 sequences of C57BL/6ByJ and 1 29P3/J mouse strains with different alleles of Snc. Using Gpr70 sequence va riation between the C57BL/6ByJ and 129P3/J strains, we conducted a high-res olution analysis of the chromosomal localization of the Gpr70 and Sac loci in the F-2 hybrids and 129.B6-Sac partially congenic mice originating from these two strains, The Gpr70 gene maps proximal to Sac, which demonstrates that they are different loci.