Identification of organic anion transporting polypeptide 4 (Oatp4) as a major full‐length isoform of the liver‐specific transporter‐1 (rlst‐1) in rat liver

Abstract
A novel organic anion transporting polypeptide (Oatp)41 was isolated from rat liver that is 35 amino acids longer than the reported rat liver specific organic anion transporter (rlst)‐1 and exhibits a 64% amino acid sequence identity with the human OATP‐C (LST‐1/OATP2; gene symbol SLC21A6). When expressed in Xenopus laevis oocytes, Oatp4 (Slc21a10) mediated polyspecific uptake of a variety of organic anions including taurocholate (K m∼27 μM), bromosulfophthalein (K m∼1.1 μM) and steroid conjugates. Based on nuclease protection analysis Oatp4 appears to be the predominant transcript in rat liver indicating that rlst‐1 plays a minor role in overall hepatic organic anion uptake.