➦ Human OAT4 (Organic Anion Transporter 4) is highly expressed at the luminal membrane of kidney proximal tubule cells and in placenta. Interestingly, OAT4 exists specific in human and primates, but not in rodents. As an asymmetric carrier OAT4 mediates the reabsorption of conjugated endogenous steroid hormones like estrone sulfate and DHEAS from primary urine and it transports organic anions accumulated in the cell by OAT1 and OAT3 in the outward direction by exchanging against extracellular chloride ions.
| Main localization: | Kidney, placenta |
| Transporter assay: | Uptake transporter assay (potential inhibitors or substrates) |
| Probe substrates: | Estrone-3-sulfate (ES) |
| Probe inhibitors: | Probenecid, Sulfobromophthalein (BSP) |
| Regulatory relevance: | − |
| Important interacting drugs: | Methotrexate, Ochratoxin A, Pitavastatin, Tetracycline, Olmesartan, Probenecid, Ketoprofen, Losartan, Furosemide, Ibuprofen, Indomethacin |
➦ Concentration dependent inhibition of hOAT4-mediated ES uptake by the probe inhibitor BSP
