Visualization and molecular analysis of nuclear import of protein kinase CK2 subunits in living cells.
We have generated fusion proteins between the subunits of CK2 and GFP and characterized their behaviour in living cells. The expressed fusion proteins were functional and interacted with endogenous CK2. Imaging of NIH3T3 cells expressing low level of GFP-CK2alpha or GFP-CK2beta showed that both proteins were mostly nuclear in interphase. Both CK2 subunits contain nuclear localization domains that target them independently to the nucleus. Once in the nucleus, both subunits diffused rapidly in the nucleoplasm. In mitotic cells, CK2 subunits were dispersed throughout the cytoplasm and were not associated to chromatin. Our data are compatible with the idea that each subunit can translocate individually to the nucleus to interact with each other or with important cellular partners. Understanding the molecular mechanisms which regulate the dynamic localization of CK2 subunits will be of central importance.
Martel
V
V
INSERM EMI 0104/BRCE, DBMS, CEA, Grenoble, France.
Filhol
O
O
Nueda
A
A
Gerber
D
D
Benitez
M J
MJ
Cochet
C
C
D016475:3T3 Cells; D021581:Active Transport, Cell Nucleus; D000818:Animals; D047390:Casein Kinase II; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology* / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D008938:Mitosis; D010957:Plasmids; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
D002843:Chromatin; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases