Serine/threonine-protein kinase involved in transcription regulation. Phosphorylates the mus-8/ubc2 ubiquitin-conjugating enzyme (E2), leading to monoubiquitination of histone H2B and the silencing of telomeric-associated genes. Also required for histone H3 methylation. Necessary for the recovery from pheromone-induced growth arrest in the cell cycle G1 phase (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] Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. CDC2/CDKX subfamily. Truncated N-terminus.