TRANSLOCATION OF LOOPS REGULATES TRANSPORT ACTIVITY OF MITOCHONDRIAL ADP-ATP CARRIER DEDUCED FROM FORMATION OF A SPECIFIC INTERMOLECULAR DISULFIDE BRIDGE CATALYZED BY COPPER-O-PHENANTHROLINE
TRANSLOCATION OF LOOPS REGULATES TRANSPORT ACTIVITY OF MITOCHONDRIAL ADP-ATP CARRIER DEDUCED FROM FORMATION OF A SPECIFIC INTERMOLECULAR DISULFIDE BRIDGE CATALYZED BY COPPER-O-PHENANTHROLINE
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DOI：
10.1074/jbc.270.49.29548
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发表时间：
1995-12-08
影响因子：
4.8
通讯作者：
TERADA, H
中科院分区：
文献类型：
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作者：
MAJIMA, E;IKAWA, K;TERADA, H
交联剂铜-邻菲咯啉络合物（Cu（OP）（2））特异性地导致牛亚线粒体颗粒中30-kDa ADP/ATP载体的量减少，主要与由载体的交联二聚体组成的60-kDa蛋白质的形成相关。而Cu（OP）（2）对线粒体无影响。ADP通过载体通过亚线粒体颗粒膜的运输被发现被抑制与分子间交联的进展平行。对交联位点的分析表明，二硫键仅在面向基质空间的一对第一环中的两个Cys（56）残基之间形成。转运抑制剂bongkrekic acid（锁定载体的m-态构象）对Cu（OP）（2）催化的二硫键形成没有影响，但羧基糖苷（通过从胞质侧作用锁定C-态构象）完全抑制交联。这些结果表明，ADP/ATP载体作为二聚体形式发挥作用，并且一对第一环在m-状态下突出到基质空间中，但在c-状态下可能侵入膜中。因此，有人建议，一对第一环作为一个门，它的开放和关闭是由他们的易位调节。
The cross-linking reagent copper-o-phenanthroline complex (Cu(OP)(2)) specifically caused a decrease in the amount of the 3O-kDa ADP/ATP carrier in bovine submitochondrial particles associated predominantly with formation of a 60-kDa protein consisting of a cross-linked dimer of the carrier. However, Cu(OP)(2) had no effect on mitochondria. The transport of ADP via the carrier through submitochondrial particle membranes was found to be inhibited in parallel with the progress of intermolecular cross-linking. Analysis of the cross-linked site showed that a disulfide bridge was formed only between two Cys(56) residues in a pair of the first loops facing the matrix space. The transport inhibitor bongkrekic acid, which locks the m-state conformation of the carrier, had no effect on disulfide bridge formation catalyzed by Cu(OP)(2), but carboxyatractyloside, which locks the c-state conformation by acting from the cytosolic side, completely inhibited the cross-linking. These results show that the ADP/ATP carrier functions as a dimer form, and a pair of the first loops protrudes into the matrix space in the m-state, but possibly intrudes into the membrane in the c-state. Thus, it is suggested that a pair of the first loops acts as a gate and that its opening and closing are regulated by their translocation.