Relationship between the Ag-Nor Proteins and the Functional Changes in Nucleoli of the Rat Hepatocytes Stimulated by Cortisol and by Partial Hepatectomy
In the interphase cell nucleus, the ribosomal genes are located in the fibrillar centers and in the associated dense fibrillar component of the nucleolus (Hernandez-Verdun, 1983; 1986; Goessens, 1984). Some acidic proteins are associated with the fibrillar components and in particular with the highly decondensed chromatin of the nucleolus. These proteins are selectively stained by silver using the method already described for visualizing proteins of metaphase Nucleolar Organizer Regions; for this reason they are called Ag-NOR proteins. These proteins are involved in transcription (Howell, 1982) suggesting they have a role in the structural-functional organization of the nucleolar components. Nucleolin, the major component of Ag-NOR proteins, might be involved in rRNA maturation (Herrera and Olson, 1986) and it has been shown to induce chromatin decondensation by binding to histone H1 (Erard et al., 1988).
KeywordsNucleolar Organizer Region rRNA Synthesis Dense Fibrillar Component Fibrillar Center Nucleolar Component
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