Efflux properties of basolateral peptide transporter in human intestinal cell line Caco-2
Efflux properties of basolateral peptide transporter in human intestinal cell line Caco-2
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DOI：
10.1007/s00424-004-1326-x
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发表时间：
2004-11-01
影响因子：
4.5
通讯作者：
Inui, K
中科院分区：
文献类型：
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作者：
Irie, M;Terada, T;Inui, K
小肽和一些生物活性化合物通过顶端H+偶联肽转运蛋白1（PEPT 1）和基底外侧肽转运蛋白从小肠吸收。在这里，我们研究了Caco-2细胞中的基底外侧肽转运蛋白的外排特性，使用两种策略，外排测量和跨上皮转运甘氨酰肌氨酸（Gly-Sar）的动力学分析。[C-14]Gly-Sar通过基底外侧膜的流出不受外部pH的显著影响。两种方法均显示基底外侧肽转运蛋白在流出方向上是可饱和的，并且亲和力低于流入方向。对于两种肽类药物，基底外侧肽转运蛋白在膜两侧的底物识别没有差异。利用PEPT 1和基底外侧肽转运蛋白的动力学参数，构建了Gly-Sar在Caco-2细胞中转运的计算模型。模拟结果与实验数据吻合较好。我们的研究结果表明，基底外侧肽转运蛋白的底物亲和力是明显不对称的，但pH依赖性和底物特异性是对称的两个方向的运输。Gly-Sar在Caco-2细胞中的行为可以通过描述肽转运蛋白的数学模型来预测。
Small peptides and some pharmacologically active compounds are absorbed from the small intestine by the apical H+-coupled peptide transporter 1 (PEPT1) and the basolateral peptide transporter. Here we investigated the efflux properties of the basolateral peptide transporter in Caco-2 cells using two strategies, efflux measurements and a kinetic analysis of transepithelial transport of glycylsarcosine (Gly-Sar). [C-14]Gly-Sar efflux through the basolateral membrane was not affected significantly by the external pH. Both approaches revealed that the basolateral peptide transporter was saturable in the efflux direction, and that the affinity was lower than that in the influx direction. For two peptide-like drugs, there was no difference in substrate recognition by the basolateral peptide transporter between the two sides of the membrane. Using the kinetic parameters of PEPT1 and the basolateral peptide transporter, a computational model of Gly-Sar transport in Caco-2 cells was constructed. The simulation fitted the experimental data well. Our findings suggested that substrate affinity of the basolateral peptide transporter is apparently asymmetric, but pH-dependence and substrate specificity are symmetric for the two directions of transport. The behaviour of Gly-Sar in Caco-2 cells could be predicted by a mathematical model describing the peptide transporters.