Interaction of kyotorphin and brain peptide transporter in synaptosomes prepared from rat cerebellum:: implication of high affinity type H+/peptide transporter PEPT2 mediated transport system
Interaction of kyotorphin and brain peptide transporter in synaptosomes prepared from rat cerebellum:: implication of high affinity type H+/peptide transporter PEPT2 mediated transport system
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DOI：
10.1016/s0304-3940(99)00540-6
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发表时间：
1999-08-20
影响因子：
2.5
通讯作者：
Yamamoto, A
中科院分区：
文献类型：
--
作者：
Fujita, T;Kishida, T;Yamamoto, A
高亲和力型 H+/肽协同转运蛋白 PEPT2 优先在肾脏中表达，负责上皮小管中二肽和三肽的重吸收。有趣的是，最近从大鼠大脑中克隆了 PEPT2。然而，关于大脑中肽转运蛋白活性的信息非常少。在本研究中，我们使用从大鼠小脑制备的突触体研究了京都啡肽（L-酪氨酰-L-精氨酸）与肽转运蛋白的相互作用。在 H+ 梯度存在的情况下，通过测量放射性标记的甘氨酰肌氨酸 (Gly-Sar) 的摄取来评估肽转运蛋白的活性，Gly-Sar 是肽转运蛋白的典型底物。京都啡肽竞争性抑制大鼠小脑突触体中 Gly-Sar 的摄取，抑制常数 (K-i) 为 30 +/- 4 μM。这种摄取特性与PEPT2非常接近，肌肽（β-丙氨酰-L-组氨酸）也抑制Gly-Sar的摄取，另一方面，TRH不与肽转运蛋白相互作用。使用特异性引物的RT-PCR显示大鼠小脑中存在PEPT2 mRNA。总的来说，这些结果表明大鼠小脑中的功能性肽转运系统可能是高亲和力转运蛋白 PEPT2。 (C) 1999 Elsevier Science Ireland Ltd. 保留所有权利。
High-affinity type H+/peptide cotransporter PEPT2 is preferentially expressed in the kidney, and is responsible for reabsorption of di- and tripeptides in epithelial tubules. Interestingly, PEPT2 has been recently cloned from rat brain. However, there is very little information available on the peptide transporter activity in the brain. In the present study, we investigated the interaction of kyotorphin (L-tyrosyl-L-arginine) with the peptide transporter using synaptosomes prepared from rat cerebellum. The activity of the peptide transporter was assessed by measuring the uptake of radiolabeled glycyl-sarcosine (Gly-Sar), which is a prototypical substrate for the peptide transporter, in the presence of H+ gradient. Kyotorphin competitively inhibited the uptake of Gly-Sar with an inhibitory constant (K-i) of 30 +/- 4 mu M in rat cerebellum synaptosomes. This uptake property is very close to that of PEPT2, Carnosine (beta-alanyl-L-histidine) also inhibited the uptake of Gly-Sar, on the other hand, TRH did not interact with the peptide transporter. RT-PCR using specific primers revealed that PEPT2 mRNA exists in cerebellum in rat. Taken collectively, these results indicate that the functional peptide transport system in rat cerebellum might be the high affinity transporter PEPT2. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.