Casein kinases are operationally defined by their preferential utilization of acidic proteins such as caseins as substrates. Can phosphorylate a large number of proteins. May have a role in DNA repair mechanism and support vegetative growth of the cells. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Monomer. Present in vegetative cells. Autophosphorylated. Belongs to the protein kinase superfamily. CK1 Ser/Thr protein kinase family. Casein kinase I subfamily. The gene for this protein is duplicated in strains AX3 and AX4. These strains contain a duplication of a segment of 750 kb of chromosome 2 compared to the corresponding sequence in strain AX2.