VRK3, also known as inactive serine/threonine-protein kinase, belongs to the protein kinase superfamily. In both human and mouse, this gene has substitutions at several residues within the ATP binding motifs that in other kinases have been shown to be required for catalysis. In vitro assays indicate the protein lacks phosphorylation activity. The protein, however, likely retains its substrate binding capability. VRK3 is widely expressed in human tissues and its protein localizes to the nucleus. Recombinant human VRK3 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.