Murakami H, Blobel G, Pain D
Laboratory of Cell Biology, Rockefeller University, Howard Hughes Medical Institute, New York, NY 10021.
Proc Natl Acad Sci U S A. 1993 Apr 15;90(8):3358-62. doi: 10.1073/pnas.90.8.3358.
An integral mitochondrial membrane protein (p32) of yeast has previously been molecularly cloned and sequenced and suggested to function as a mitochondrial import receptor. However, this protein has also been proposed to function as phosphate translocator [Guérin, B., Bukusoglu, C., Rakotomanana, F. & Wohlrab, H. (1990) J. Biol. Chem. 265, 19736-19741; Phelps, A., Schobert, C.T. & Wohlrab, H. (1991) Biochemistry 30, 248-252]. Here we have purified p32 after expression of its gene in Escherichia coli and assayed its ability to bind to various preproteins containing signal sequences for protein translocation into mitochondria, chloroplasts, or the endoplasmic reticulum. Our data suggest that p32 contains a binding site specific for the signal sequence region of mitochondrial preproteins. These data are consistent with the previous assignment of p32 as an import receptor and are discussed with regard to the apparently conflicting assignment of this protein as phosphate translocator.
酵母的一种线粒体内膜蛋白（p32）此前已被分子克隆和测序，并被认为作为线粒体输入受体发挥作用。然而，该蛋白也被认为可作为磷酸转运体[Guérin, B., Bukusoglu, C., Rakotomanana, F. & Wohlrab, H. (1990) J. Biol. Chem. 265, 19736 - 19741; Phelps, A., Schobert, C.T. & Wohlrab, H. (1991) Biochemistry 30, 248 - 252]。在此，我们在大肠杆菌中表达其基因后纯化了p32，并检测了它与各种含有向线粒体、叶绿体或内质网转运蛋白的信号序列的前体蛋白结合的能力。我们的数据表明，p32含有一个对线粒体前体蛋白信号序列区域具有特异性的结合位点。这些数据与之前将p32认定为输入受体的结果一致，并就该蛋白作为磷酸转运体这一明显矛盾的认定进行了讨论。
