Rospert S, Dubaquié Y, Gautschi M
Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle, Germany.
Cell Mol Life Sci. 2002 Oct;59(10):1632-9. doi: 10.1007/pl00012490.
Nascent-polypeptide-associated complex (NAC) is a heterodimeric complex which can reversibly bind to eukaryotic ribosomes. NAC is located in direct proximity to newly synthesized polypeptide chains as they emerge from the ribosome. Although its function is thought to be conserved from yeast to humans our current knowledge about what NAC actually does in a living cell is incomplete. It has been suggested that NAC is a (i) dynamic component of the ribosomal exit tunnel, providing a shield for nascent polypeptides, (ii) negative regulator of translocation into the endoplasmic reticulum and (iii) positive regulator of translocation into the mitochondria. However, none of these hypotheses is generally accepted. Moreover, the individual subunits of NAC have been implicated in processes related to transcription rather than translation, and it is currently under debate whether NAC might be a protein of dual function. This review attempts to summarize the data from different fields and to discuss the partly controversial results in a common context.
新生多肽相关复合体（NAC）是一种异源二聚体复合体，它能够可逆地结合到真核生物核糖体上。当新合成的多肽链从核糖体中出现时，NAC直接位于其附近。尽管人们认为其功能从酵母到人类都是保守的，但我们目前对于NAC在活细胞中实际作用的了解并不完整。有人提出，NAC是（i）核糖体出口通道的动态组成部分，为新生多肽提供保护；（ii）向内质网转运的负调节因子；（iii）向线粒体转运的正调节因子。然而，这些假说都未被普遍接受。此外，NAC的各个亚基与转录而非翻译相关的过程有关，目前对于NAC是否可能是一种具有双重功能的蛋白质仍存在争议。这篇综述试图总结来自不同领域的数据，并在一个共同的背景下讨论部分有争议的结果。
