Serine/threonine-protein kinase component of the BUR kinase complex involved in transcription regulation. This complex phosphorylates 'Ser-120' of the UBC2/RAD6 ubiquitin-conjugating enzyme (E2), leading to monoubiquitination of histone H2B, the localization of the PAF1 complex to the chromatin, and the silencing of telomeric-associated genes. Also required for histone H3 'Lys-4' trimethylation. May phosphorylate the 'Ser-5' of the RBP1 carboxy-terminal domain (CTD) repeats. Necessary for the recovery from pheromone-induced growth arrest in the cell cycle G1 phase. The kinase activity of the complex requires the presence of BUR2. 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 BUR kinase complex composed of SGV1/BUR1 and BUR2. Interacts with BUR2 and RBP1. Present with 2070 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. CDC2/CDKX subfamily.