To obtain the subject new protein having a specific amino acid sequenced, being a G-protein conjugated type receptor derived from human stomach or small intestine, and useful as e.g. a reagent for developing receptor binding assay system or screening compounds proposed for a medicine.

This protein is a new G-protein conjugated type receptor protein (salt) having an amino acid sequence identical with or essentially identical with an amino acid sequence of the formula, and a useful as e.g. a reagent for developing receptor binding assay system or screening compounds proposed for a medicine; the DNA of this protein is useful for the drug design based on the comparison with structurally similar ligand receptors, as a probe in gene diagnoses, PCR primer, etc. This protein is obtained by the following process: a human stomach-derived cDNA synthesized from the corresponding human stomach-derived mRNA is amplified by PCR process using a primer consisting of part of the base sequence of the cDNA to effect cloning, and the resultant gene is then integrated into a vector and expressed in host cells.