Plays a complex role in regulating the basal catalytic activity of the alpha subunit. The tetrameric holoenzyme CK2, composed of two alpha and two beta subunits, phosphorylates the transcription factor GBFl, resulting in stimulation of its DNA binding activity (PubMed:7696877). CK2 phosphorylates the transcription factor PIF1 after an exposure to light, resulting in a proteasome-dependent degradation of PIF1 and promotion of photomorphogenesis (PubMed:21330376). CK2 phosphorylates translation initiation factors. May participate in the regulation of the initiation of translation (PubMed:19509278, PubMed:19509420). Stimulates the binding of CCA1 to promoters (Probable). Heterotetramer of two catalytic alpha subunits and two regulatory beta subunits (PubMed:7696877, PubMed:19509278). Interacts with CCA1 (PubMed:9724822). Interacts with LHY (PubMed:10535927). A number of isoforms are produced. According to EST sequences. Phosphorylated by alpha subunit. Belongs to the casein kinase 2 subunit beta family.