George R, Beddoe T, Landl K, Lithgow T
School of Biochemistry, La Trobe University, Bundoora 3083, Australia.
Proc Natl Acad Sci U S A. 1998 Mar 3;95(5):2296-301. doi: 10.1073/pnas.95.5.2296.
The yeast nascent polypeptide-associated complex (NAC) is encoded by two genes, EGD1 and EGD2, and is associated with cytoplasmic ribosomes. Yeast mutants lacking NAC (Deltaegd2) are viable but suffer slight defects in the targeting of nascent polypeptides to several locations including the endoplasmic reticulum and mitochondria. If both NAC and Mft52p are missing from yeast cells, inefficient targeting of mitochondrial precursor proteins leads to defects in both mitochondrial function and morphology. We suggest that NAC provides a ribosomal environment for nascent mitochondrial targeting sequences to achieve secondary structure, thereby enhancing the efficiency of protein targeting.
酵母新生多肽相关复合体（NAC）由两个基因EGD1和EGD2编码，并与细胞质核糖体相关联。缺乏NAC的酵母突变体（Deltaegd2）能够存活，但在将新生多肽靶向包括内质网和线粒体在内的多个位置时存在轻微缺陷。如果酵母细胞中同时缺失NAC和Mft52p，线粒体前体蛋白的靶向效率低下会导致线粒体功能和形态出现缺陷。我们认为，NAC为新生的线粒体靶向序列提供了一个核糖体环境，使其能够形成二级结构，从而提高蛋白质靶向的效率。
