Substrate profiling of human vaccinia-related kinases identifies coilin, a Cajal body nuclear protein, as a phosphorylation target with neurological implications

► Peptide-chip analysis identifies basic sequences as target of VRK proteins. ► In Cajal bodies coilin interacts and is a direct target of VRK1. ► Nuclear VRK1 phosphorylates coilin in Ser184. ► VRK1(R358X) has reduced kinase activity and is located in cytosol. ► VRK1(R358X) is silenced by nonsense-decay and cannot phosphorylate coilin.