Basic region of residues 228–231 of protein kinase CK1α is involved in its interaction with axin: Binding to axin does not affect the kinase activity
✍ Scribed by Pablo Sobrado; Ana Jedlicki; Victor H. Bustos; Catherine C. Allende; Jorge E. Allende
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 148 KB
- Volume
- 94
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Protein kinase CK1, also known as casein kinase 1, participates in the phosphorylation of b-catenin, which regulates the functioning of the Wnt signaling cascade involved in embryogenesis and carcinogenesis. b-catenin phosphorylation occurs in a multiprotein complex assembled on the scaffold protein axin. The interaction of CK1a 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 CK1a 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-CK1a interaction, the effect of the presence of axin on the phosphorylating activity of CK1a was tested. It is also evident that the region of axin downstream of residues 503-562 is required for CK1a interaction. The binding of CK1a to axin fragment 292-681 does not facilitate the phosphorylation of bcatenin despite the fact that this axin fragment can also bind b-catenin. Binding of CK1a to axin is not required for the phosphorylation of axin itself and, likewise, axin does not affect the kinetic parameters of the CK1a towards casein or a specific peptide substrate.