{PDOC00006}
{PS00006; CK2_PHOSPHO_SITE}
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* Casein kinase II phosphorylation site *
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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.

-Consensus pattern: [ST]-x(2)-[DE]
                    [S or T is the phosphorylation site]

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

-Last update: May 1991 / Text revised.

[ 1] Pinna L.A.
     "Casein kinase 2: an 'eminence grise' in cellular regulation?"
     Biochim. Biophys. Acta 1054:267-284(1990).
     PubMed=2207178

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