Centrosomal anchoring of the protein kinase CK1delta mediated by attachment to the large, coiled-coil scaffolding protein CG-NAP/AKAP450.
Protein kinase CK1 (formerly termed casein kinase I) is ubiquitous in eukaryotic cells and comprises a family of as many as 14 isoforms (including splice variants) in mammalian cells. Mammalian CK1delta and CK1epsilon, which are highly related to each other, are enriched at the centrosomes in interphase cells and at the spindle during mitosis. In the present study we have isolated, using the yeast two-hybrid system, a 182 amino acid residue fragment of the centrosomal and golgi N-kinase anchoring protein (CG-NAP, also known as AKAP450), which specifically interacts with CK1delta and CK1epsilon, but not with other CK1 isoforms. The 182 amino acid residue CG-NAP fragment, or full length CG-NAP, co-immunoprecipitates with CK1delta and CK1epsilon from mammalian cells. Consistent with this association, endogenous CG-NAP/AKAP450 and CK1delta co-localize in cells. Moreover, when expressed in the presence of CK1delta the 182 amino acid residue CG-NAP fragment adopts the same sub-cellular localization as CK1delta. Strikingly, attachment of the CG-NAP fragment to the plasma membrane is sufficient to re-localize a significant level of CK1delta to the membrane. These findings support a model in which sub-cellular localization of CK1delta/epsilon molecules at the centrosome is mediated, at least in part, through the action of CG-NAP/AKAP450 and provide a potential mechanism by which the contribution to cell cycle progression by CK1delta/epsilon may be regulated.
Sillibourne
James E
JE
Biomedical Research Centre, Ninewells Hospital and Medical School, University of Dundee, Scotland DD1 9SY, UK.
Milne
Diane M
DM
Takahashi
Mikiko
M
Ono
Yoshitaka
Y
Meek
David W
DW
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000596:Amino Acids; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D047388:Casein Kinases; D002384:Catalysis; D018385:Centrosome / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011233:Precipitin Tests; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013347:Subcellular Fractions; D013379:Substrate Specificity
D054758:A Kinase Anchor Proteins; C119719:AKAP9 protein, human; D048868:Adaptor Proteins, Signal Transducing; C486537:Akap9 protein, rat; D000596:Amino Acids; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D007527:Isoenzymes; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D011494:Protein Kinases; D047388:Casein Kinases