Homeodomain Interacting Protein Kinase 4 (HIPK4)

HIPK4 can phosphorylate human p53 at the serine-9 position. Overexpression of HIPK4 resulted in decreased activity of the survivin (BIRC5) promoter, which is directly repressed by p53.The deduced human and mouse proteins contain 616 amino acids with a serine/threonine kinase domain in the N terminus and a PEST domain in the C terminus. About 50% of the residues in the HIPK4 serine/threonine kinase domain are identical to those in other known HIPK proteins. RT-PCR analysis of mouse tissues showed moderate expression of Hipk4 in lung and white adipose tissue and weak expression in brain and liver. Expression of human HIPK4 was also seen in various cancer cell lines. Transient transfection experiments with GFP-tagged HIPK4 in A549 and COS-1 cells demonstrated localization throughout the cytoplasm and weakly in nucleus.