title: Cell cycle regulatory protein p27KIP1 is a substrate and interacts with the protein kinase CK2.
abstract: The protein kinase CK2 is constituted by two catalytic (alpha and/or alpha') and two regulatory (beta) subunits. CK2 phosphorylates more than 300 proteins with important functions in the cell cycle. This study has looked at the relation between CK2 and p27(KIP1), which is a regulator of the cell cycle and a known inhibitor of cyclin-dependent kinases (Cdk). We demonstrated that in vitro recombinant Xenopus laevis CK2 can phosphorylate recombinant human p27(KIP1), but this phosphorylation occurs only in the presence of the regulatory beta subunit. The principal site of phosphorylation is serine-83. Analysis using pull down and surface plasmon resonance (SPR) techniques showed that p27(KIP1) interacts with the beta subunit through two domains present in the amino and carboxyl ends, while CD spectra showed that p27(KIP1) phosphorylation by CK2 affects its secondary structure. Altogether, these results suggest that p27(KIP1) phosphorylation by CK2 probably involves a docking event mediated by the CK2beta subunit. The phosphorylation of p27(KIP1) by CK2 may affect its biological activity.
authors.affiliation: Laboratorio de Biología Molecular de la Transducción de Señales Celulares, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Chile.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Tapia
authors.forename: Victor M
authors.initials: VM
authors.lastname: Bolanos-Garcia
authors.forename: Muhammed
authors.initials: M
authors.lastname: Sayed
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Allende
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Allende
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001345:Autoradiography; D001665:Binding Sites / Q000502:physiology; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002942:Circular Dichroism; D003001:Cloning, Molecular; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D020349:Surface Plasmon Resonance; D014982:Xenopus laevis
chemical_list: C493956:CDKN1A protein, human; C436291:CDKN1B protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D047908:Intracellular Signaling Peptides and Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D012694:Serine; D047390:Casein Kinase II