SLCO2B1 O94956

溶质载体有机阴离子转运蛋白家族成员2B1 (有机阴离子转运蛋白B) (OATP-B) (有机阴离子转运多肽相关蛋白2) (OATP-RP2) (OATPRP2) (有机阴离子转运多肽2B1) (OATP2B1) (溶质载体家族21成员9)

功能描述

介导类固醇硫酸结合物及其他特定有机阴离子的Na(+)-非依赖性转运 (PubMed:10873595, PubMed:11159893, PubMed:11932330, PubMed:12724351, PubMed:14610227, PubMed:16908597, PubMed:18501590, PubMed:20507927, PubMed:22201122, PubMed:23531488, PubMed:25132355, PubMed:26383540, PubMed:27576593, PubMed:28408210, PubMed:29871943, PubMed:34628357)。负责通过合体滋养层基底膜转运雌酮3-硫酸盐(E1S)，突显其在胎盘吸收胎儿来源的硫酸化类固醇（包括类固醇激素前体硫酸脱氢表雄酮(DHEA-S)）中的潜在作用 (PubMed:11932330, PubMed:12409283)。也促进肝细胞基底/窦状隙膜对硫酸化类固醇的摄取，因此解释了肝脏有机阴离子清除的主要部分 (PubMed:11159893)。介导硫酸化类固醇的肠道摄取 (PubMed:12724351, PubMed:28408210)。介导神经类固醇DHEA-S和孕烯醇酮硫酸盐(PregS)进入血脑屏障内皮细胞，作为进入大脑的第一步 (PubMed:16908597, PubMed:25132355)。也在视网膜神经元释放的神经肽（如P物质/TAC1和血管活性肠肽/VIP）的重摄取中发挥作用 (PubMed:25132355)。可能作为血红素转运蛋白，通过血红素加氧酶/HMOX2并以不依赖TFRC的方式促进细胞铁的利用 (PubMed:35714613)。也转运血红素副产物粪卟啉III(CPIII)，并可能参与其在肝脏的处置 (PubMed:26383540)。介导其他底物的摄取，如前列腺素D2(PGD2)、E1(PGE1)和E2(PGE2)、牛磺胆酸盐、L-甲状腺素、白三烯C4和血栓烷B2 (PubMed:10873595, PubMed:14610227, PubMed:19129463, PubMed:29871943, Ref.25)。可能有助于调节睾丸跨血睾屏障的有机化合物转运 (Probable)。表现出对pH敏感的底物特异性，这可能归因于结合位点的质子化状态，并导致在酸性微环境中底物转运受到刺激 (PubMed:14610227, PubMed:19129463, PubMed:22201122)。确切的转运机制尚未被完全解析，但最可能涉及阴离子交换，将有机底物的细胞摄取与阴离子化合物的外排耦合 (PubMed:19129463, PubMed:20507927, PubMed:26277985)。碳酸氢根/HCO3(-)作为可能的反向阴离子与有机阴离子进行交换 (PubMed:19129463)。胞质谷氨酸在胎盘中也可能作为反向阴离子 (PubMed:26277985)。向内的质子梯度也被认为是E1S摄取的驱动力，其(H(+):E1S)化学计量比为(1:1) (PubMed:20507927)。 {ECO:0000269|PubMed:10873595, ECO:0000269|PubMed:11159893, ECO:0000269|PubMed:11932330, ECO:0000269|PubMed:12409283, ECO:0000269|PubMed:12724351, ECO:0000269|PubMed:14610227, ECO:0000269|PubMed:16908597, ECO:0000269|PubMed:18501590, ECO:0000269|PubMed:19129463, ECO:0000269|PubMed:20507927, ECO:0000269|PubMed:22201122, ECO:0000269|PubMed:23531488, ECO:0000269|PubMed:25132355, ECO:0000269|PubMed:26277985, ECO:0000269|PubMed:26383540, ECO:0000269|PubMed:27576593, ECO:0000269|PubMed:29871943, ECO:0000269|PubMed:34628357, ECO:0000269|PubMed:35714613, ECO:0000269|Ref.25, ECO:0000305|PubMed:35307651}.; FUNCTION: [Isoform 3]: 具有与全长亚型1相当的雌酮3-硫酸盐(E1S)转运活性。 {ECO:0000269|PubMed:23531488}.

组织特异性

Strongly expressed in the liver, at the sinusoidal membrane of the hepatocytes (PubMed:10873595, PubMed:11159893, PubMed:23531488). Expressed in the kidney (PubMed:11159893). Expressed in placental trophoblasts and syncytiotrophoblast (PubMed:11159893, PubMed:11932330, PubMed:12409283, PubMed:26277985). Expressed in the small intestine (PubMed:10873595, PubMed:11159893, PubMed:12724351, PubMed:23531488, PubMed:28408210). Expressed in the blood-brain barrier, in endothelial cells of brain capillaries (PubMed:11159893, PubMed:25132355). Expressed in the retina, in the inner nuclear layer and the inner plexiform layer (PubMed:25132355). Expressed in skelettal muscles (PubMed:23531488). In testis, primarily localized to the basal membrane of Sertoli cells and weakly expressed within the tubules (PubMed:10873595, PubMed:11159893, PubMed:35307651). Also expressed in pancreas, lung, heart, colon, ovary and spleen (PubMed:10873595, PubMed:11159893). Expressed in fetal brain, heart, kidney, liver, lung, skeletal muscle, spleen and pancreas (PubMed:10873595).

亚细胞定位

Cell membrane