Dependence of the mitochondrial uptake of triiodothyronine (T3) in rat kidney on cytosolic T3-binding protein.
Dependence of the mitochondrial uptake of triiodothyronine (T3) in rat kidney on cytosolic T3-binding protein.
复制标题
大鼠肾脏中线粒体摄取三碘甲状腺原氨酸 (T3) 对胞质 T3 结合蛋白的依赖性。
DOI：
10.1210/endo-119-3-1063
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发表时间：
1986
期刊：
影响因子：
4.8
通讯作者：
K. Yamauchi
中科院分区：
文献类型：
--
作者：
K. Hashizume;M. Kobayashi;T. Miyamoto;K. Yamauchi
用离体大鼠肾组织研究了胞浆T3结合蛋白（CTBP）对线粒体T3摄取的影响。在不存在CTBP的情况下，[125 I]T3摄取进入线粒体是时间依赖性的。在培养液中加入CTBP显著增加线粒体[125 I]T3摄取。当线粒体与[125 I]T3-CTBP复合物一起孵育时，[125 I]T3进入线粒体的摄取仍然是时间依赖性的，但[125 I]T3的掺入量大于与游离[125 I]T3孵育的线粒体。尽管过量未标记T3对[125 I]T3摄取无明显抑制作用，但过量未标记T3-CTBP复合物可明显抑制[125 I]T3摄取。T3-CTBP复合物的抑制程度与浓度有关。然而，[125 I]T3-CTBP复合物孵育线粒体产生的[125 I] T3摄取不被不饱和CTBP抑制。当膜与游离[125 I]T3或[125 I]T3-CTBP复合物孵育时，观察到[125 I]T3与线粒体外膜结合;与[125 I]T3-CTBP复合物孵育的膜中[125 I] T3结合的量更大。通过加入未标记的T3-CTBP复合物来取代与[125 I]T3-CTBP复合物孵育的膜结合的[125 I]T3。这些结果表明，线粒体T3的摄取介导的T3与CTBP的先前的结合，和摄取可能是由T3-CTBP复合物结合到其在线粒体外膜的受体调节。
The effect of cytosolic T3-binding protein (CTBP) on mitochondrial T3 uptake was investigated by using rat kidney tissue in vitro. [125I]T3 uptake into mitochondria was time dependent in the absence of CTBP. Addition of CTBP to the incubation medium significantly increased mitochondrial [125I]T3 uptake. When mitochondria were incubated with a [125I]T3-CTBP complex, [125I]T3 uptake into mitochondria continued to be time dependent, but the amount of [125I]T3 incorporated was greater than in mitochondria incubated with free [125I]T3. Although [125I]T3 uptake was not significantly inhibited by an excess of unlabeled T3, it was markedly inhibited by an excess of unlabeled T3-CTBP complex. The degree of inhibition was related to the concentration of T3-CTBP complex. However, [125I]T3 uptake produced by incubation of mitochondria with [125I]T3-CTBP complex was not inhibited by unsaturated CTBP. [125I]T3 binding to outer mitochondrial membranes was observed when the membranes were incubated with free [125I]T3 or [125I]T3-CTBP complex; the amount of [125I]T3 bound was greater in the membranes incubated with [125I]T3-CTBP complex. [125I]T3 binding to the membranes incubated with [125I]T3-CTBP complex was displaced by the addition of unlabeled T3-CTBP complex. These results suggest that mitochondrial T3 uptake is mediated by previous binding of T3 to CTBP, and that the uptake is possibly regulated by T3-CTBP complex binding to its receptor in the outer mitochondrial membrane.