Schwartz M P, Huang S, Matouschek A
Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA.
J Biol Chem. 1999 Apr 30;274(18):12759-64. doi: 10.1074/jbc.274.18.12759.
Precursor proteins must be at least partially unfolded during import into mitochondria, but their actual conformation during translocation is not known. Are proteins fully unfolded and threaded through the import machinery amino acid by amino acid, or do they retain some partial structure? The folding pathway of most proteins in vitro contains a partially folded intermediate known as the molten globule state, and it has been suggested that proteins are in the molten globule state during translocation across membranes. Here we show that precursors are normally fully unfolded during import into mitochondria. However, precursors containing residual structure can be imported, if less efficiently.
前体蛋白在导入线粒体的过程中必须至少部分解折叠，但其在转运过程中的实际构象尚不清楚。蛋白质是完全解折叠并逐个氨基酸穿过导入机制，还是保留一些部分结构？大多数蛋白质在体外的折叠途径包含一种称为熔球态的部分折叠中间体，有人提出蛋白质在跨膜转运过程中处于熔球态。在这里，我们表明前体蛋白在导入线粒体的过程中通常是完全解折叠的。然而，含有残余结构的前体蛋白也可以被导入，只是效率较低。
