期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：1
页码：343-347
DOI：10.1073/pnas.76.1.343
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The mitochondrial F1-ATPase consists of five nonidentical subunits that are synthesized outside the mitochondria and imported across both mitochondrial membranes to the matrix side of the inner membrane. In order to study the mechanism of this import, we synthesized the F1-ATPase subunits of yeast either in vitro (in a reticulocyte lysate programmed with yeast RNA) or in vivo (in pulsed and pulsed-chased yeast spheroplasts). Both in vitro and in vivo, each of the three largest ATPase subunits was synthesized as a larger precursor. When the precursors that had been synthesized in vitro were incubated with isolated yeast mitochondria, they were converted to "mature" subunits that were no longer susceptible to externally added proteases. The uptake of the subunit into the mitochondria was thus accompanied by conversion of the precursor. Since uptake of precursors into mitochondria was independent of protein synthesis and since the precursors could also be detected in vivo, the transfer of proteins from the cytosol across both mitochondrial membranes does not occur by vectorial translation. Instead, the proteins destined for import are first made outside the mitochondria as precursors and only subsequently transported into the mitochondria. This step is accompanied by proteolytic conversion of the mature subunit.
