Pfanner N, Tropschug M, Neupert W
Cell. 1987 Jun 19;49(6):815-23. doi: 10.1016/0092-8674(87)90619-2.
The role of nucleoside triphosphates (NTPs) in mitochondrial protein import was investigated with the precursors of N. crassa ADP/ATP carrier, F1-ATPase subunit beta, F0-ATPase subunit 9, and fusion proteins between subunit 9 and mouse dihydrofolate reductase. NTPs were necessary for the initial interaction of precursors with the mitochondria and for the completion of translocation of precursors from the mitochondrial surface into the mitochondria. Higher levels of NTPs were required for the latter reactions as compared with the early stages of import. Import of precursors having identical presequences but different mature protein parts required different levels of NTPs. The sensitivity of precursors in reticulocyte lysate to proteases was decreased by removal of NTPs and increased by their readdition. We suggest that the hydrolysis of NTPs is involved in modulating the folding state of precursors in the cytosol, thereby conferring import competence.
利用粗糙脉孢菌ADP/ATP载体、F1 - ATP酶β亚基、F0 - ATP酶9亚基的前体以及9亚基与小鼠二氢叶酸还原酶之间的融合蛋白，研究了核苷三磷酸（NTPs）在线粒体蛋白质导入中的作用。NTPs对于前体与线粒体的初始相互作用以及前体从线粒体表面转运到线粒体内的过程的完成是必需的。与导入早期阶段相比，后期反应需要更高水平的NTPs。具有相同前导序列但不同成熟蛋白部分的前体的导入需要不同水平的NTPs。去除NTPs会降低网织红细胞裂解物中前体对蛋白酶的敏感性，而重新添加NTPs则会增加其敏感性。我们认为，NTPs的水解参与调节胞质溶胶中前体的折叠状态，从而赋予导入能力。
