A protein and DNA encoding the same are useful as preventives/remedies for diseases such as hypoglycemia, etc. The protein of the present invention is also useful as a reagent for screening a compound that inhibits the binding of the protein of the present invention to IRAP (insulin responsive aminopeptidase) or to GLUT4 (glucose transporter 4). The compound that inhibits the binding of the protein of the present invention to IRAP or GLUT4 is useful as a preventive/remedy for diseases, e.g., hyperglycemia, diabetes mellitus, etc.