CK2a1, Active

CK2 α (also termed casein kinase II α) is a serine-threonine protein kinase whose targets include many critical regulators of cellular growth. It is highly expressed in a lympho pro-liferative disease of cattle and in many human cancers. Overexpression of the CK2 α catalytic subunit in lymphocytes of transgenic mice leads to T cell lymphoma (1). The highest CK2 activity is found in mouse testicles and brain, followed by spleen, liver, lung, kidney and heart (2). The activity values were directly correlated with the protein expression level of the CK2α (catalytic subunit). The α subunit is only detected in brain and testicles. By contrast, Northern blot analyses of the CK2 α mRNA shows the strongest signals to be present in brain, liver, heart and lung. In kidney, spleen and testicles mRNAs is only weakly detectable. ICBP90, a transcription factor exhibiting antiapoptotic property, has several putative CK2 phosphorylation sites. ICBP90 is more efficiently phosphorylated by the free CK2 α subunit than by the heterotetrameric CK2 (α, β) (3). Thus, CK2 α is an important regulator of the transcriptional activity of ICBP90 and therefore of the antiapoptotic properties of ICBP90.