PROSITE documentation PDOC00006
Casein kinase II phosphorylation site


Casein kinase II (CK-2) is a protein serine/threonine kinase whose activity is independent of cyclic nucleotides and calcium. CK-2 phosphorylates many different proteins. The substrate specificity [1] of this enzyme can be summarized as follows:

 (1) Under comparable conditions Ser is favored over Thr.
 (2) An acidic residue (either Asp or Glu) must be present three residues from
     the C-terminal of the phosphate acceptor site.
 (3) Additional acidic  residues in  positions +1, +2, +4, and +5 increase the
     phosphorylation rate.  Most  physiological  substrates  have at least one
     acidic residue in these positions.
 (4) Asp is preferred to Glu as the provider of acidic determinants.
 (5) A basic residue at the N-terminal  of the  acceptor  site  decreases  the
     phosphorylation rate, while an acidic one will increase it.

This pattern is found in most of the known physiological substrates.

Last update:

May 1991 / Text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

CK2_PHOSPHO_SITE, PS00006; Casein kinase II phosphorylation site  (PATTERN with a high probability of occurrence!)


1AuthorsPinna L.A.
TitleCasein kinase 2: an 'eminence grise' in cellular regulation?
SourceBiochim. Biophys. Acta 1054:267-284(1990).
PubMed ID2207178

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