Transport activity of MCT1 expressed in Xenopus oocytes is increased by interaction with carbonic anhydrase
Transport activity of MCT1 expressed in Xenopus oocytes is increased by interaction with carbonic anhydrase
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DOI：
10.1074/jbc.m503081200
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发表时间：
2005-12-02
影响因子：
4.8
通讯作者：
Deitmer, JW
中科院分区：
文献类型：
--
作者：
Becker, HM;Hirnet, D;Deitmer, JW
注射碳酸酐酶亚型II（CA）到非洲爪蟾卵母细胞增加的H+流量通过大鼠单羧酸转运体亚型1（MCT 1）在卵母细胞中表达的速率。MCT 1活性通过pH选择性微电极测量的细胞内H+浓度的变化来评估。CA诱导的增加率的H+流量介导的MCT 1不抑制乙氧唑胺（10 μ M），并不依赖于存在的添加CO2/HCO 3-，但抑制注射抗体抗CA。删除MCT 1的C末端大大降低了其转运速率，并消除了CA的转运促进作用。注射CA加速CO2/HCO 3-诱导的酸化几倍，这是由乙氧基唑胺阻断，是独立的MCT 1的表达。质谱法证实了CA注射到青蛙卵母细胞中的活性。与下拉测定，我们证明了特异性结合的CA的MCT 1，这是不是归因于C末端的MCT 1。我们的研究结果表明，CA增强MCT 1的运输活性，独立于其酶反应中心，大概是通过结合到MCT 1。
Injection of carbonic anhydrase isoform II (CA) into Xenopus frog oocytes increased the rate of H+ flux via the rat monocarboxylate transporter isoform 1 (MCT1) expressed in the oocytes. MCT1 activity was assessed by changes of intracellular H+ concentration measured by pH-selective microelectrodes during application of lactate. CA-induced augmentation of the rate of H+ flux mediated by MCT1 was not inhibited by ethoxyzolamide (10 mu M) and did not depend on the presence of added CO2/HCO3- but was suppressed by injection of an antibody against CA. Deleting the C terminus of the MCT1 greatly reduced its transport rate and removed transport facilitation by CA. Injected CA accelerated the CO2/HCO3--induced acidification severalfold, which was blocked by ethoxyzolamide and was independent of MCT1 expression. Mass spectrometry confirmed activity of CA as injected into the frog oocytes. With pulldown assays we demonstrated a specific binding of CA to MCT1 that was not attributed to the C terminus of MCT1. Our results suggest that CA enhances MCT1 transport activity, independent of its enzymatic reaction center, presumably by binding to MCT1.