Functional characterization of human organic anion transporting polypeptide B (OATP-B) in comparison with liver-specific OATP-C

Pharm Res. 2001 Sep;18(9):1262-9. doi: 10.1023/a:1013077609227.


Purpose: To assess the functional characteristics of human organic anion transporter B (OATP-B) in comparison with those of the known, liver-specific OATP-C.

Methods: OATP-B or -C was expressed in HEK293 cells or Xenopus oocytes, and uptakes of estradiol-17beta-glucuronide and estrone-3-sulfate were measured using radiolabeled compounds.

Results: OATP-C transported both estrone-3-sulfate and estradiol-17beta-glucuronide, whereas OATP-B transported only the former. OATP-C-mediated uptake of estrone-3-sulfate exhibited biphasic saturation kinetics, whereas transports of estradiol-17beta-glucuronide by OATP-C and estrone-3-sulfate by OATP-B followed single-saturation kinetics. Inhibition kinetics showed that only the high-affinity site for estrone-3-sulfate on OATP-C was shared with glucuronide conjugates. Uptake of [3H]estrone-3-sulfate by OATP-B was inhibited by sulfate conjugates but not by glucuronide conjugates, whereas its uptake by OATP-C was inhibited by both types of conjugates.

Conclusions: OATP-B accepted sulfate conjugates of steroids but not glucuronide conjugates, whereas OATP-C transported both types of steroid conjugates. Transport of estrone-3-sulfate by OATP-B and -C followed single- and biphasic-saturation kinetics, respectively, and the high-affinity site on OATP-C was the same as that for estradiol-17beta-glucuronide. Other OATPs, OATP-A and OATP-8, reportedly exhibit different preferences for steroid conjugates, and the specific recognition of sulfate conjugates seems to be unique to OATP-B.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Estradiol / analogs & derivatives*
  • Estradiol / metabolism
  • Estrogens, Conjugated (USP) / metabolism
  • Estrone / analogs & derivatives*
  • Estrone / metabolism
  • Humans
  • Kinetics
  • Liver-Specific Organic Anion Transporter 1 / analysis
  • Liver-Specific Organic Anion Transporter 1 / metabolism*
  • Oocytes / metabolism
  • Organic Anion Transporters / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Substrate Specificity
  • Xenopus


  • Estrogens, Conjugated (USP)
  • Liver-Specific Organic Anion Transporter 1
  • Organic Anion Transporters
  • SLCO2B1 protein, human
  • estradiol-17 beta-glucuronide
  • Estrone
  • Estradiol
  • estrone sulfate