Related Experiment Video
Updated: Oct 2, 2026

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Kinetic properties of p53 phosphorylation by the human vaccinia-related kinase 1
Ramiro Barcia1, Susana López-Borges, Francisco M Vega
1Instituto de Biología Molecular y Celular del Cáncer, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, E-37007, Spain.
Abstract:
The vaccinia-related kinase 1 (VRK1) protein is a nuclear Ser-Thr kinase that phosphorylates p53 in Thr18. We have determined the enzyme properties regarding its different substrates. VRK1 has a high affinity for ATP (K(m) 50 microM) and is thus saturated by the intracellular concentration of ATP in vivo. VRK1 uses preferentially magnesium, but is also functional with manganese and zinc. The VRK1 protein is autophosphorylated in multiple residues without effect on its activity. One autophosphorylated residue, T355, is within the VRK1 regulatory carboxy terminus. The kinase phosphorylates p53 with a K(m) of 1 microM and is well suited to respond to the variations of intracellular p53 concentration, which fluctuates as a response to different types of cellular stress.
Related Concept Videos
PI3K/mTOR/AKT Signaling Pathway
Covalently Linked Protein Regulators
These groups modify specific amino acids in a protein.
Abnormal Proliferation
Protein Kinases and Phosphatases
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
Interactions Between Signaling Pathways
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
The JAK-STAT Signaling Pathway

