A novel sodium-dependent bile acid transporter protein, an Na.sup.+/H.sup.+ exchange transporter protein, a P-type ATPase protein and a vanilloid receptor protein, and polynucleotides encoding these proteins are useful in screening preventives/remedies for hyperlipemia, arteriosclerosis, genital diseases or digestive diseases; respiratory diseases, renal diseases or digestive diseases; pancreatic diseases, central nerve diseases, digestive diseases or respiratory diseases; inflammatory diseases, rheumatoid diseases or diabetic neurosis; etc.