Basic region of residues 228-231 of protein kinase CK1alpha is involved in its interaction with axin: binding to axin does not affect the kinase activity.
Protein kinase CK1, also known as casein kinase 1, participates in the phosphorylation of beta-catenin, which regulates the functioning of the Wnt signaling cascade involved in embryogenesis and carcinogenesis. beta-catenin phosphorylation occurs in a multiprotein complex assembled on the scaffold protein axin. The interaction of CK1alpha from Danio rerio with mouse-axin has been studied using a pull-down assay that uses fragments of axin fused to glutathione S transferase, which is bound to glutathione sepharose beads. The results indicate that the three lysines present in the basic region of residues 228-231 of CK1alpha are necessary for the binding of CK1 to axin. Lysine 231 is particularly important in this interaction. In order to define the relevance of the axin-CK1alpha interaction, the effect of the presence of axin on the phosphorylating activity of CK1alpha was tested. It is also evident that the region of axin downstream of residues 503-562 is required for CK1alpha interaction. The binding of CK1alpha to axin fragment 292-681 does not facilitate the phosphorylation of beta-catenin despite the fact that this axin fragment can also bind beta-catenin. Binding of CK1alpha to axin is not required for the phosphorylation of axin itself and, likewise, axin does not affect the kinetic parameters of the CK1alpha towards casein or a specific peptide substrate.
Sobrado
Pablo
P
Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Independencia 1027, Santiago 8380453, Chile.
Jedlicki
Ana
A
Bustos
Victor H
VH
Allende
Catherine C
CC
Allende
Jorge E
JE
D000818:Animals; D060466:Axin Protein; D001665:Binding Sites; D048128:Casein Kinase Ialpha / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008239:Lysine; D051379:Mice; D009842:Oligopeptides / Q000737:chemistry*; D010766:Phosphorylation; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D015027:Zebrafish; D029961:Zebrafish Proteins; D051176:beta Catenin
D060466:Axin Protein; C495267:CTNNB1 protein, mouse; D003598:Cytoskeletal Proteins; D009842:Oligopeptides; D012097:Repressor Proteins; D015534:Trans-Activators; D029961:Zebrafish Proteins; D051176:beta Catenin; C495269:ctnnb1 protein, zebrafish; D005982:Glutathione Transferase; D048128:Casein Kinase Ialpha; D008239:Lysine