Ness S A, Weiss R L
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Proc Natl Acad Sci U S A. 1987 Oct;84(19):6692-6. doi: 10.1073/pnas.84.19.6692.
The large subunit of carbamoyl phosphate synthase A [carbon-dioxide: L-glutamine amido-ligase (ADP-forming, carbamate-phosphorylating), EC 6.3.5.5] from Neurospora crassa is encoded by a nuclear gene but is localized in the mitochondrial matrix. We have utilized N. crassa strains that produce both normal and carboxyl-terminal-truncated forms of carbamoyl phosphate synthase A to ask whether the carboxyl terminus affects import of the carbamoyl phosphate synthase A precursor. We found that carboxyl-terminal-truncated precursors were directed to mitochondria but that they were imported less efficiently than full-length proteins that were synthesized in the same cytoplasm. Our results suggest that effective import of proteins into mitochondria requires appropriate combinations of targeting sequences and three-dimensional structure.
粗糙脉孢菌的氨甲酰磷酸合酶A [二氧化碳：L-谷氨酰胺酰胺连接酶（形成ADP，氨甲酰磷酸化），EC 6.3.5.5] 的大亚基由一个核基因编码，但定位于线粒体基质中。我们利用能产生正常形式和羧基末端截短形式的氨甲酰磷酸合酶A的粗糙脉孢菌菌株，来探究羧基末端是否会影响氨甲酰磷酸合酶A前体的导入。我们发现，羧基末端截短的前体被导向线粒体，但与在同一细胞质中合成的全长蛋白质相比，它们的导入效率较低。我们的结果表明，蛋白质有效导入线粒体需要靶向序列和三维结构的适当组合。
