A novel human organic anion transporting polypeptide localized to the basolateral hepatocyte membrane

Am J Physiol Gastrointest Liver Physiol. 2000 Jan;278(1):G156-64. doi: 10.1152/ajpgi.2000.278.1.G156.


We cloned and expressed a new organic anion transporting polypeptide (OATP), termed human OATP2, (OATP-C, LST-1; symbol SLC21A6), involved in the uptake of various lipophilic anions into human liver. The cDNA encoding OATP2 comprised 2073 base pairs, corresponding to a protein of 691 amino acids, which were 44% identical to the known human OATP. An antibody directed against the carboxy terminus localized OATP2 to the basolateral membrane of human hepatocytes. Northern blot analysis indicated a strong expression of OATP2 only in human liver. Transport mediated by recombinant OATP2 and its localization were studied in stably transfected Madin-Darby canine kidney strain II (MDCKII) and HEK293 cells. Confocal microscopy localized recombinant OATP2 protein to the lateral membrane of MDCKII cells. Substrates included 17beta-glucuronosyl estradiol, monoglucuronosyl bilirubin, dehydroepiandrosterone sulfate, and cholyltaurine. 17beta-Glucuronosyl estradiol was a preferred substrate, with a Michaelis-Menten constant value of 8.2 microM; its uptake was Na(+) independent and was inhibited by sulfobromophthalein, with a inhibition constant value of 44 nM. Our results indicate that OATP2 is important for the uptake of organic anions, including bilirubin conjugates and sulfobromophthalein, in human liver.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / genetics
  • Animals
  • Anion Transport Proteins
  • Blotting, Northern
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Carrier Proteins / physiology
  • Cell Line
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • Dogs
  • Estradiol / analogs & derivatives
  • Estradiol / pharmacokinetics
  • Fluorescent Antibody Technique
  • Glucuronates / pharmacokinetics
  • Humans
  • Intracellular Membranes / metabolism*
  • Liver / cytology
  • Liver / metabolism*
  • Molecular Sequence Data
  • Recombinant Proteins / metabolism
  • Tissue Distribution


  • 17-glucuronosylestradiol
  • Anion Transport Proteins
  • Carrier Proteins
  • DNA, Complementary
  • Glucuronates
  • Recombinant Proteins
  • Estradiol

Associated data

  • GENBANK/H62893