Mammalian T1R3 sweet taste receptors

Abstract

The present invention provides isolated nucleic acid and amino acid sequences of sweet taste receptors, the receptors comprising consisting of a monomer or homodimer of a T1R3 G-protein coupled receptor polypeptide, antibodies to such receptors, methods of detecting such nucleic acids and receptors, and methods of screening for modulators of sweet and amino acid taste receptors.

1 . An isolated homodimeric taste receptor, the receptor comprising two T1R3 polypeptides, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31.  
     
     
         2 . The isolated receptor of  claim 1 , wherein the T1R3 polypeptide comprises an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31.  
     
     
         3 . The isolated receptor of  claim 1 , wherein the T1R3 polypeptide is encoded by a nucleotide sequence comprising SEQ ID NO:14, 19, 22, 24, or 30.  
     
     
         4 . The isolated receptor of  claim 1 , wherein the T1R3 polypeptides are non-covalently linked.  
     
     
         5 . The isolated receptor of  claim 1 , wherein the T1R3 polypeptides are covalently linked.  
     
     
         6 . The isolated receptor of  claim 1 , wherein the receptor binds to sweet taste ligands.  
     
     
         7 . The isolated receptor of  claim 6 , wherein the sweet taste ligand is a naturally occurring sugar selected from the group consisting of glucose, fructose, galactose, sucrose, maltose, and lactose.  
     
     
         8 . The isolated receptor of  claim 1 , wherein the receptor has G protein coupled receptor activity.  
     
     
         9 . The isolated receptor of  claim 1 , wherein the receptor specifically binds to antibodies raised against SEQ ID NO:15, 20, 23, 25, or 31.  
     
     
         10 . The isolated receptor of  claim 1 , wherein the T1R3 polypeptides are recombinant.  
     
     
         11 . A host cell comprising the isolated receptor of  claim 10 , wherein the host cell does not express T1R1 or T1R2.  
     
     
         12 . An isolated homodimeric taste receptor, the receptor consisting of two T1R3 polypeptides, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that has 90% identity to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31.  
     
     
         13 . An isolated monomeric taste receptor, the receptor consisting of one T1R3 polypeptide, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31.  
     
     
         14 . The isolated receptor of  claim 13 , wherein the T1R3 polypeptide comprises an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31.  
     
     
         15 . The isolated receptor of  claim 13 , wherein the T1R3 polypeptide is encoded by a nucleotide sequence comprising SEQ ID NO:14, 19, 22, 24, or 30.  
     
     
         16 . The isolated receptor of  claim 13 , wherein the receptor binds to sweet taste ligands.  
     
     
         17 . The isolated receptor of  claim 13 , wherein the sweet taste ligand is a naturally occurring sugar selected from the group consisting of glucose, fructose, galactose, sucrose, maltose, and lactose.  
     
     
         18 . The isolated receptor of  claim 13 , wherein the receptor has G protein coupled receptor activity.  
     
     
         19 . The isolated receptor of  claim 13 , wherein the T1R3 polypeptide is recombinant.  
     
     
         20 . A host cell comprising the isolated receptor of  claim 19 , wherein the host cell does not express T1R1 or T1R2.  
     
     
         21 . A host cell expressing a recombinant taste receptor, the receptor comprising a T1R3 polypeptide, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31, wherein the cell does not express T1R1 or T1R2.  
     
     
         22 . A method of identifying a compound that modulates taste signal transduction in taste cells, the method comprising the steps of 
 (i) contacting the compound with a homodimeric taste receptor comprising two T1R3 polypeptides, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25 or 31; and    (ii) determining the functional effect of the compound upon the receptor, thereby identifying a compound that modulates taste signal transduction.    
     
     
         23 . The method of  claim 22 , wherein the T1R3 polypeptides are non-covalently linked.  
     
     
         24 . The method of  claim 22 , wherein the T1R3 polypeptides are covalently linked.  
     
     
         25 . The method of  claim 22 , wherein the receptor is recombinant.  
     
     
         26 . The method of  claim 22 , wherein the receptor has G protein coupled receptor activity.  
     
     
         27 . The method of  claim 22 , wherein the functional effect is measured in vitro.  
     
     
         28 . The method of  claim 27 , wherein the functional effect is a physical effect.  
     
     
         29 . The method of  claim 27 , wherein the receptor is linked to a solid phase.  
     
     
         30 . The method of  claim 27 , wherein the functional effect is determined by measuring binding of a compound to the receptor.  
     
     
         31 . The method of  claim 30 , wherein the functional effect is determined by measuring binding of a compound to the extracellular domain of the receptor.  
     
     
         32 . The method of  claim 22 , wherein the receptor is expressed in a cell or cell membrane, wherein the cell does not express T1R1 or T1R2.  
     
     
         33 . The method of  claim 32 , wherein the functional effect is a physical effect.  
     
     
         34 . The method of  claim 33 , wherein the functional effect is determined by measuring ligand binding to the receptor.  
     
     
         35 . The method of  claim 34 , wherein the functional effect is determined by measuring binding of a compound to the extracellular domain of the receptor.  
     
     
         36 . The method of  claim 32 , wherein the functional effect is a chemical or phenotypic effect.  
     
     
         37 . The method of  claim 36 , wherein the functional effect is determined by measuring changes in intracellular cAMP, IP3, or Ca 2+ .  
     
     
         38 . The method of  claim 32 , wherein the cell is a mammalian cell.  
     
     
         39 . The method of  claim 38 , wherein the cell is a human cell.  
     
     
         40 . A method of identifying a compound that modulates taste signal transduction in taste cells, the method comprising the steps of 
 (i) contacting the compound with cell expressing a homodimeric taste receptor comprising two T1R3 polypeptides, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31; wherein the cell does not express T1R1 and T1R2; and    (ii) determining the functional effect of the compound upon the receptor, thereby identifying a compound that modulates taste signal transduction.    
     
     
         41 . The method of  claim 40 , wherein the T1R3 polypeptides are non-covalently linked.  
     
     
         42 . The method of  claim 40 , wherein the T1R3 polypeptides are covalently linked.  
     
     
         43 . A method of identifying a compound that modulates taste signal transduction in taste cells, the method comprising the steps of 
 (i) contacting the compound with a monomeric taste receptor comprising one T1R3 polypeptide, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25 or 31; and    (ii) determining the functional effect of the compound upon the receptor, thereby identifying a compound that modulates taste signal transduction.    
     
     
         44 . A method of identifying a compound that modulates taste signal transduction in taste cells, the method comprising the steps of 
 (i) contacting the compound with cell expressing a monomeric taste receptor comprising one T1R3 polypeptide, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31; wherein the cell does not express T1R1 or T1R2; and    (ii) determining the functional effect of the compound upon the receptor, thereby identifying a compound that modulates taste signal transduction.    
     
     
         45 . A method of identifying a compound that modulates taste signal transduction in taste cells, the method comprising the steps of 
 (i) contacting the compound with cell expressing a taste receptor comprising a T1R3 polypeptide, wherein the T1R3 polypeptide is encoded by a nucleotide sequence that hybridizes under highly stringent hybridization conditions to a nucleotide sequence encoding an amino acid sequence of SEQ ID NO:15, 20, 23, 25, or 31; wherein the cell does not express T1R1 and T1R2; and    (ii) determining the functional effect of the compound upon the receptor, thereby identifying a compound that modulates taste signal transduction.