核仁和核仁蛋白

核仁是位于细胞核内的非膜结构。电子显微镜下的核仁从形态上可以分为三层结构包括纤维中心区(FC)、高密度纤维区(DFC)和颗粒区(GC)。核仁内的蛋白有核糖体蛋白和非核糖体蛋白两种。利用蛋白质组学方法已经鉴定了350多种核仁蛋白,其中包括80多种核糖体蛋白。核仁是核糖体合成的场所,核仁中的非核糖体蛋白对核糖体的生物合成起关键调控作用。核仁不仅是细胞内通讯和核糖体：RNA加工的中心,而且在细胞周期、细胞增殖和衰老中起重要调控作用;核仁也是tRNA、mRNA和其它类型小分子RNA加工的场所。因此核仁是一个多功能的细胞生命活动中心。

The Nucleolus and Nucleolar Proteins

Nucleolus is nonmembrane subnuclear organelle. Nucleolus is morphologically separated into three distinct concentric components under electron microscopy: the inner fibrillar center (FC), the middle dense fibrillar component (DFC), and the outer granular component (GC). There are two kinds of proteins including ribosomal proteins and nonribosomal proteins in nucleolus. The extensive proteomic analysis shows that nucleolus has a surprisingly large protein complexity of more 350 proteins including more than 80 ribosomal proteins. The major activity in the nucleolus is ribosome biogenesis; the nonribosomal proteins in nucleolus play key roles on riobosome biogenesis. Moreover, recent work suggests that the nucleolus is the center of the cellular communication and that it plays important roles in cell cycle control, cell proliferation and aging. Also, nucleolus is the site where tRNA, mRNA and other small RNA molecules are been processed. The notion of "plurifunctional' nucleolus is now well established. Thus convincing evidence shows nucleolus may play a central role in the control of gene expression.