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Closed Access item The human vaccinia-related kinase 1 (VRK1) phosphorylates threonine-18 within the mdm-2 binding site of the p53 tumour suppressor protein

Authors:López-Borges, Susana
Lazo, Pedro A.
Keywords:VRK1, p53, mdm2, kinase
Issue Date:2000
Citation:Oncogene 19(32): 3656-3664 (2000)
Abstract:The tumour suppressor p53 protein integrates multiple signals regulating cell cycle progression and apoptosis. This regulation is mediated by several kinases that phosphorylate speci®c residues in the di erent functional domains of the p53 molecule. The human VRK1 protein is a new kinase related to a poxvirus kinase, and more distantly to the casein kinase 1 family. We have characterized the biochemical properties of human VRK1 from HeLa cells. VRK1 has a strong autopho- sphorylating activity in several Ser and Thr residues. VRK-1 phosphorylates acidic proteins, such as phosvitin and casein, and basic proteins such as histone 2b and myelin basic protein. Because some transcription factors are regulated by phosphorylation, we tested as substrates the N-transactivation domains of p53 and c-Jun fused to GST. Human c-Jun is not phosphorylated by VRK1. VRK1 phosphorylates murine p53 in threonine 18. This threonine is within the p53 hydrophobic loop (residues 13 ± 23) required for the interaction of p53 with the cleft of its inhibitor mdm-2. The VRK1 C-terminus domain (residues 268 ± 396) that contains a nuclear localization signal targets the protein to the nucleus, as determined by using fusion proteins with the green ¯uorescent protein. We conclude that VRK1 is an upstream regulator of p53 that belongs to a new signalling pathway. Oncogene (2000) 19, 3656 ± 3664.
URI:http://hdl.handle.net/10261/6988
Appears in Collections:(IBMCC) Artículos

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