The Nucleolus and Nucleolar Proteins

Abstract: 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.

CSTR: 32200.14.cjcb.2004.03.0011