Sodium-independent organic anion transporter which shows high specificity for estrone sulfate, dehydroepiandrosterone sulfate, and the mycotoxin ochratoxin A (OTA) (PubMed:15068970, PubMed:16150593). Transport of OTA is strongly inhibited by estrone sulfate and probenecid, and to a lesser extent by 2,4-dichlorophenoxyacetic acid (2,4-D) and salicylate (PubMed:15068970). Transport of estrone sulfate is inhibited by various steroid sulfate conjugates including dehydroepiandrosterone sulfate, alpha-naphthyl sulfate, beta-estradiol sulfate, 4-methylumbelliferyl sulfate and p-nitrophenyl sulfate (but not minoxidil sulfate) (PubMed:16150593). Specifically expressed in kidney, where it localizes to proximal tubules of the outer medulla (at protein level) (PubMed:15068970, PubMed:16150593). Not detected in other tissues tested (PubMed:15068970). Belongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family.