Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
Comp Biochem Physiol C Toxicol Pharmacol. 2010 Apr;151(3):393-9. doi: 10.1016/j.cbpc.2010.01.005. Epub 2010 Jan 14.
The human liver-specific organic anion transporting polypeptides (OATPs) 1B1 and 1B3 are involved in the elimination of numerous xenobiotics and drugs. Although dogs are frequently used for toxicologic and pharmacokinetic characterization of novel drugs, nothing is known about their OATP1B1/1B3 ortholog. Therefore, we cloned and characterized the first canine organic anion transporting polypeptide from dog liver, termed Oatp1b4. The isolated Oatp1b4 cDNA comprises 3661 base pairs (bp) with an open reading frame of 2076bp, encoding a 692-amino acid protein with a molecular mass of approximately 85kDa. The Oatp1b4 gene is approximately 61kb long and has a similar organization as the human OATP1B1 and OATP1B3 with 13 exons identical in length. Northern blot analysis shows that Oatp1b4 is predominantly expressed in the liver. Oatp1b4 mediates sodium-independent transport of typical organic anions including bromosulfophthalein (BSP), [D-penicillamine(2,5)]enkephalin (DPDPE), estradiol-17beta-glucuronide (E17betaG), estrone-3-sulfate and taurocholate. In addition, Oatp1b4 transports the OATP1B3-specific substrate cholecystokinin octapeptide (CCK-8). Kinetic studies showed that Oatp1b4-mediated E17betaG and estrone-3-sulfate transports were monophasic with K(m) values of 5+/-1microM and 33+/-4microM, respectively. In conclusion, the cloned canine Oatp1b4 will provide additional molecular basis to further characterize the species difference of the OATP1B family members.
人肝脏特异性有机阴离子转运多肽 (OATPs) 1B1 和 1B3 参与了许多外源化学物和药物的消除。尽管狗经常被用于新药物的毒理学和药代动力学特征描述，但对其 OATP1B1/1B3 同源物一无所知。因此，我们从狗肝中克隆并鉴定了第一个犬有机阴离子转运多肽，命名为 Oatp1b4。分离的 Oatp1b4 cDNA 包含 3661 个碱基对（bp），开放阅读框为 2076bp，编码一个 692 个氨基酸的蛋白质，分子量约为 85kDa。Oatp1b4 基因约 61kb 长，与人类 OATP1B1 和 OATP1B3 的组织相似，有 13 个相同长度的外显子。Northern blot 分析表明，Oatp1b4 主要在肝脏中表达。Oatp1b4 介导包括溴磺酞（BSP）、[D-青霉胺（2,5）]脑啡肽（DPDPE）、雌二醇-17β-葡糖苷酸（E17βG）、雌酮-3-硫酸盐和牛磺胆酸钠在内的典型有机阴离子的钠离子非依赖性转运。此外，Oatp1b4 还转运 OATP1B3 特异性底物胆囊收缩素八肽（CCK-8）。动力学研究表明，Oatp1b4 介导的 E17βG 和雌酮-3-硫酸盐转运呈单相位，K(m) 值分别为 5±1μM 和 33±4μM。总之，克隆的犬 Oatp1b4 将为进一步表征 OATP1B 家族成员的种间差异提供额外的分子基础。
