Wang S, Sakai H, Wiedmann M
Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York 10021, USA.
J Cell Biol. 1995 Aug;130(3):519-28. doi: 10.1083/jcb.130.3.519.
We demonstrate that nascent polypeptide-associated complex (NAC) is one of the first cytosolic factors that newly synthesized nascent chains encounter. When NAC is present, nascent chains are segregated from the cytosol until approximately 30 amino acids in length, a finding consistent with the well-documented protease resistance of short ribosome-associated nascent chains. When NAC is removed, the normally protected nascent chains are susceptible to proteolysis. Therefore NAC, by covering COOH-terminal segments of nascent chains on the ribosome, perhaps together with ribosomal proteins, forms a protective environment for regions of nascent chains just emerging from the peptidyl transferase center. Since NAC is not a core ribosomal protein, the emergence of nascent chains from the ribosome may be more dynamic than previously thought.
我们证明新生肽相关复合物（NAC）是新合成的新生链遇到的最早的胞质因子之一。当NAC存在时，新生链与胞质分离，直到长度约为30个氨基酸，这一发现与短核糖体相关新生链有充分记录的蛋白酶抗性一致。当NAC被去除时，通常受到保护的新生链易受蛋白水解作用。因此，NAC通过覆盖核糖体上新生链的COOH末端片段，可能与核糖体蛋白一起，为刚从肽基转移酶中心出现的新生链区域形成一个保护环境。由于NAC不是核糖体核心蛋白，新生链从核糖体的出现可能比以前认为的更具动态性。
