Putative organic anion antiporter with apparent broad substrate specificity. Recognizes various substrates including thyroid hormone L-thyroxine, prostanoids such as prostaglandin E1 and E2, bile acids such as taurocholate, glycolate and glycochenodeoxycholate and peptide hormones such as L-arginine vasopressin, likely operating in a tissue-specific manner (PubMed:10873595, PubMed:14631946, PubMed:16971491, PubMed:19129463, PubMed:30063921). The transport mechanism, its electrogenicity and potential tissue-specific counterions remain to be elucidated (Probable). Mediates transport of tryptophan, phenyalanine and tyrosine (PubMed:39206635). {ECO:0000269|PubMed:10873595, ECO:0000269|PubMed:14631946, ECO:0000269|PubMed:16971491, ECO:0000269|PubMed:19129463, ECO:0000269|PubMed:30063921, ECO:0000269|PubMed:39206635, ECO:0000305}. [Isoform 1]: Mediates transport of steroid hormone precursors dehydroepiandrosterone 3-sulfate and estrone 3-sulfate. . [Isoform 2]: Mediates transport of steroid hormone precursors dehydroepiandrosterone 3-sulfate and estrone 3-sulfate. . [Isoform 5]: Mediates transport of steroid hormone precursors dehydroepiandrosterone 3-sulfate and estrone 3-sulfate. . This is the function of SLCO3A1 (solute carrier organic anion transporter family member 3A1, ENSG00000176463).