Compartmentation of the nucleolar processing proteins in the granular component is a CK2-driven process.
To analyze the compartmentation of nucleolar protein complexes, the mechanisms controlling targeting of nucleolar processing proteins onto rRNA transcription sites has been investigated. We studied the reversible disconnection of transcripts and processing proteins using digitonin-permeabilized cells in assays capable of promoting nucleolar reorganization. The assays show that the dynamics of nucleolar reformation is ATP/GTP-dependent, sensitive to temperature, and CK2-driven. We further demonstrate the role of CK2 on the rRNA-processing protein B23. Mutation of the major CK2 site on B23 induces reorganization of nucleolar components that separate from each other. This was confirmed in assays using extracts containing B23 mutated in the CK2-binding sites. We propose that phosphorylation controls the compartmentation of the rRNA-processing proteins and that CK2 is involved in this process.
Institut Jacques Monod, Centre National de la Recherche Scientifique, University Paris VI and Paris VII, 75251 Paris Cedex 05, France.
Emilie
E
Louvet
Henriette Roberte
HR
Junéra
Isabelle
I
Berthuy
Danièle
D
Hernandez-Verdun
D000255:Adenosine Triphosphate / Q000378:metabolism; D047390:Casein Kinase II / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002466:Cell Nucleolus / Q000502:physiology* / Q000648:ultrastructure; D004256:DNA Polymerase I / Q000235:genetics; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D011499:Protein Processing, Post-Translational; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D012335:RNA, Ribosomal; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D047390:Casein Kinase II; D004256:DNA Polymerase I