Ungermann C, Neupert W, Cyr D M
Institut für Physiologische Chemie, Universität München, Germany.
Science. 1994 Nov 18;266(5188):1250-3. doi: 10.1126/science.7973708.
The entry of segments of preproteins of defined lengths into the matrix space of mitochondria was studied. The mitochondrial chaperone Hsp70 (mtHsp70) interacted with proteins emerging from the protein import channel and stabilized translocation intermediates across the membranes in an adenosine triphosphate-dependent fashion. The chaperone bound to the presequence and mature parts of preproteins. In the absence of mtHsp70 binding, preproteins with less than 30 to 40 residues in the matrix diffused out of mitochondria. Thus, protein translocation was reversible up to a late stage. The import channels in both mitochondrial membranes constitute a passive pore that interacts weakly with polypeptide chains entering the matrix.
研究了特定长度前体蛋白片段进入线粒体基质空间的过程。线粒体伴侣蛋白Hsp70（mtHsp70）与从蛋白质输入通道出来的蛋白质相互作用，并以三磷酸腺苷依赖的方式稳定跨膜转运中间体。该伴侣蛋白与前体蛋白的前导序列和成熟部分结合。在没有mtHsp70结合的情况下，基质中少于30至40个残基的前体蛋白会从线粒体中扩散出来。因此，蛋白质转运在后期之前都是可逆的。线粒体内外膜中的输入通道构成一个被动孔道，与进入基质的多肽链相互作用较弱。
