Cellular component

casein kinase II complex

A protein complex that possesses protein serine/threonine kinase activity, and contains two catalytic alpha subunits and two regulatory beta subunits. Protein kinase CK2 complexes are found in nearly every subcellular compartment, and can phosphorylate many protein substrates in addition to casein.

Note that this term represents a location and not a function; the activity possessed by this complex is mentioned in the definition for the purpose of describing and distinguishing the complex.