Argan C, Lusty C J, Shore G C
J Biol Chem. 1983 Jun 10;258(11):6667-70.
A higher molecular weight precursor (Mr = 39,000) to the liver mitochondrial matrix enzyme, ornithine carbamyltransferase (Mr = 36,000), is imported and processed by heart mitochondria in vitro in a manner similar to liver mitochondria. In both systems, however, an additional 37-kDa ornithine carbamyltransferase polypeptide appears, but this arises from nonspecific events and, therefore, does not represent a bona fide intermediate in the overall processing sequence. Our experiments demonstrate that the outer mitochondrial membrane of mitochondria contains a protease-sensitive (5 micrograms of trypsin or chymotrypsin/ml, 15 min at 2 degrees C), salt-resistant (1.0 M KCl) protein which is required to maintain import functions. In addition, functional post-translational import requires a component of the reticulocyte lysate (i.e. cytosol) that is used for initially synthesizing precursor enzyme. The component is retained by Sephadex G-25. Import of Sephadex G-25-excluded precursor is restored by fresh reticulocyte lysate but not by a combination of other additives, including Mg2+, K+, ATP, ADP, Pi, succinate, and total translation mixture (minus lysate).
肝脏线粒体基质酶鸟氨酸氨甲酰基转移酶（分子量36,000）的一种分子量更高的前体（分子量39,000），在体外可被心脏线粒体以与肝脏线粒体相似的方式导入并加工。然而，在这两个系统中，都会出现一种额外的37 kDa鸟氨酸氨甲酰基转移酶多肽，但这是由非特异性事件产生的，因此并不代表整个加工序列中的真正中间体。我们的实验表明，线粒体的外膜含有一种对蛋白酶敏感（2℃下，5μg胰蛋白酶或糜蛋白酶/ ml，15分钟）、耐盐（1.0 M KCl）的蛋白质，该蛋白质是维持导入功能所必需的。此外，功能性翻译后导入需要用于最初合成前体酶的网织红细胞裂解物（即胞质溶胶）的一种成分。该成分可被葡聚糖G - 25保留。葡聚糖G - 25排除的前体的导入可通过新鲜的网织红细胞裂解物恢复，但不能通过其他添加剂的组合恢复，这些添加剂包括Mg2 +、K +、ATP、ADP、Pi、琥珀酸盐和总翻译混合物（不含裂解物）。
