Patent ID: 8173378

Claim:
A method for modifying ligand affinity of a GPCRα 1A , the method comprising the steps of: (a) providing a cell; and (b) coexpressing both a GPCRα 1A and a polypeptide in the cell; (c) measuring ligand affinity of the GPCRα 1A in the cell which expresses both the GPCRα 1A and the polypeptide, and in a cell which expresses the GPCRα 1A and does not express the polypeptide; and (d) comparing a result obtained from the cell which expresses both the GPCRα 1A and the polypeptide, with a result obtained from the cell which expresses the GPCRα 1A and does not express the polypeptide, the polypeptide being: (i) a polypeptide consisting of an amino acid sequence of SEQ ID NO: 1; or (ii) a polypeptide encoded by a polynucleotide consisting of a nucleotide sequence of SEQ ID NO: 2; wherein GPCRα 1A affinity increases or decreases in the presence of the polypeptide.