Mammalian sweet taste receptors
The present invention provides isolated nucleic acid and amino acid sequences of sweet taste receptors comprising two heterologous G-protein coupled receptor polypeptides from the T1R family of sensory G-protein coupled receptors, antibodies to such receptors, methods of detecting such nucleic acids and receptors, and methods of screening for modulators of sweet taste receptors.
1. An isolated receptor, wherein the receptor comprises a first polypeptide and a second polypeptide, wherein the first polypeptide has at least 93% amino acid sequence identity to SEQ ID NO:20, or at least 94% amino acid sequence identity to SEQ ID NO:23, and wherein the second polypeptide has at least 92% amino acid sequence identity to SEQ ID NO:8.
2. The isolated receptor of claim 1 , wherein the receptor is a sweet taste receptor.
3. The isolated receptor of claim 1 , wherein the first polypeptide has the amino acid sequence of SEQ ID NO:20.
4. The isolated receptor of claim 1 , wherein the first polypeptide has the amino acid sequence of SEQ ID NO:23.
5. The isolated receptor of claim 1 , wherein the first polypeptide is encoded by a nucleotide sequence of SEQ ID NO:19 or SEQ ID NO:22.
6. The isolated receptor of claim 1 , wherein the second polypeptide has the amino acid sequence of SEQ ID NO:8.
7. The isolated receptor of claim 1 , wherein the second polypeptide is encoded by a nucleotide sequence of SEQ ID NO:11.
8. The isolated receptor of claim 1 , wherein the first polypeptide is recombinant.
9. A host cell comprising the isolated receptor of claim 8 .
10. The isolated receptor of claim 1 , wherein the first polypeptide and the second polypeptide are recombinant.
11. A host cell expressing the recombinant receptor of claim 10 .
12. The isolated receptor of claim 1 , wherein the second polypeptide is recombinant.
13. A host cell expressing the recombinant receptor of claim 12 .
14. The isolated receptor of claim 1 , wherein the first polypeptide and the second polypeptide are non-covalently linked.
15. The isolated receptor of claim 1 , wherein the first polypeptide and the second polypeptide are covalently linked.
16. The isolated receptor of claim 1 , wherein the receptor specifically binds to an antibody that specifically binds to a polypeptide comprising SEQ ID NO:20 or SEQ ID NO:23.
17. A method of identifying a compound that activates or inhibits signal transduction in cells, the method comprising the steps of:
(i) contacting the compound with a cell expressing the receptor of claim 1 in the plasma membrane of the cell; and
(ii) determining a functional effect of the compound upon the receptor, wherein said functional effect is binding to the receptor or having an effect on the activity of the receptor, thereby identifying a compound that activates or inhibits signal transduction.
18. The method of claim 17 , wherein the first polypeptide has the amino acid sequence of SEQ ID NO: 20 or 23.
19. The method of claim 17 , wherein the second polypeptide has the amino acid sequence of SEQ ID NO:8.
20. The method of claim 17 , wherein the functional effect is determined by measuring binding of the compound to the receptor.
21. The method of claim 17 , wherein the functional effect is determined by measuring ligand binding to the receptor.
22. The method of claim 17 , wherein the functional effect is a chemical or phenotypic effect.
23. The method of claim 17 , wherein the functional effect is determined by measuring changes in intracellular cAMP, IP3, or Ca2+.
24. The method of claim 17 , wherein the cell is a mammalian cell.
25. The method of claim 24 , wherein the cell is a human cell.
26. The method of claim 17 , wherein the first polypeptide and the second polypeptide are non-covalently linked.
27. The method of claim 17 , wherein the first polypeptide and the second polypeptide are covalently linked.
28. The method of claim 17 , wherein the first polypeptide and the second polypeptide are both recombinant.
29. A method of identifying a compound that activates or inhibits signal transduction in cells, the method comprising the steps of: (i) contacting the compound with a cell expressing the receptor of claim 1 in the plasma membrane of the cell, and (ii) determining a functional effect of the compound upon the receptor, wherein said functional effect is binding to the receptor or having an effect on the activity of the receptor, thereby identifying a compound that activates or inhibits signal transduction, wherein the receptor specifically binds compound, and at least one of the first and second polypeptides is recombinant.