Recombinant human Complex of CDK19 and Cyclin. Recombinant human CDK1 (cyclin dependent kinase 12), encompassing amino acids 696-1082. This construct contains an N-terminal GST-tag and includes a Thrombin Cleavage Site to facilitate removal of the GST portion. Recombinant human Cyclin K (CCNK), full length, encompassing amino acids 2-580(end). This construct contains an N-terminal GST-tag and includes a Thrombin Cleavage Site to facilitate removal of the GST portion. These two recombinant proteins were co-expressed and affinity purified.