Identification and characterization of CKIP-1, a novel pleckstrin homology domain-containing protein that interacts with protein kinase CK2.
The catalytic subunits of protein kinase CK2, CK2alpha and CK2alpha', are closely related to each other but exhibit functional specialization. To test the hypothesis that specific functions of CK2alpha and CK2alpha' are mediated by specific interaction partners, we used the yeast two-hybrid system to identify CK2alpha- or CK2alpha'-binding proteins. We report the identification and characterization of a novel CK2-interacting protein, designated CKIP-1, that interacts with CK2alpha, but not CK2alpha', in the yeast two-hybrid system. CKIP-1 also interacts with CK2alpha in vitro and is co-immunoprecipitated from cell extracts with epitope-tagged CK2alpha and an enhanced green fluorescent protein fusion protein encoding CKIP-1 (i.e. EGFP-CKIP-1) when they are co-expressed. CK2 activity is detected in anti-CKIP-1 immunoprecipitates performed with extracts from non-transfected cells indicating that CKIP-1 and CK2 interact under physiological conditions. The CKIP-1 cDNA is broadly expressed and encodes a protein with a predicted molecular weight of 46,000. EGFP-CKIP-1 is localized within the nucleus and at the plasma membrane. The plasma membrane localization is dependent on the presence of an amino-terminal pleckstrin homology domain. We postulate that CKIP-1 is a non-enzymatic regulator of one isoform of CK2 (i.e. CK2alpha) with a potential role in targeting CK2alpha to a particular cellular location.
Bosc
D G
DG
Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
Graham
K C
KC
Saulnier
R B
RB
Zhang
C
C
Prober
D
D
Gietz
R D
RD
Litchfield
D W
DW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D001798:Blood Proteins / Q000737:chemistry*; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D047390:Casein Kinase II; D020134:Catalytic Domain; D002460:Cell Line; D017931:DNA Primers; D018076:DNA, Complementary; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry*; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D001798:Blood Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; C408877:PLEKHO1 protein, human; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; C039077:platelet protein P47; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases