Serine/threonine-protein kinase (PubMed:8844681, PubMed:14604523). Involved in the control of the cell cycle (By similarity). Required for entry into S-phase and mitosis (By similarity). Probable component of the kinase complex that phosphorylates the repetitive C-terminus of RNA polymerase II (By similarity). In schizonts, phosphorylates ORC1 resulting in its dissociation from DNA, relocalization to the cytoplasm and likely its degradation (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] [DNA-directed RNA polymerase] + ATP = ADP + H(+) + phospho-[DNA-directed RNA polymerase] Phosphorylation at Thr-14 or Tyr-15 inactivates the enzyme, while phosphorylation at Thr-158 activates it (By similarity). Activated by cyclin cyc-1 in vitro (By similarity). Activated by cyclin cyc-3 in vitro (By similarity). May form a complex composed of at least the catalytic subunit CRK2 and a cyclin. Expressed during the asexual blood stage including in trophozoites and schizonts. Autophosphorylates in presence of cyclin cyc-1 but not in presence of cyclin cyc-3. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. CDC2/CDKX subfamily.