Dual-specificity protein kinases: will any hydroxyl do?

Trends Biochem Sci. 1992 Mar;17(3):114-9. doi: 10.1016/0968-0004(92)90248-8.


Protein kinases are classified by the target amino acid in their substrates. Those protein kinases that phosphorylate hydroxyamino acids comprise two groups, the protein-tyrosine and protein-serine/threonine kinases, which, until recently, had been thought to be mutually exclusive. However, several new protein kinases have been discovered that, by the criterion of primary structure, would be classified as protein-serine/threonine kinases but which, surprisingly, are able to phosphorylate tyrosine residues. Even more surprising, there are reports of protein kinases that are capable of phosphorylating both tyrosine and serine/threonine residues. We review and discuss recent developments concerning these 'dal-specificity' protein kinases.

Publication types

  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Humans
  • Hydroxylation
  • Molecular Sequence Data
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / physiology*
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / physiology*
  • Saccharomyces cerevisiae
  • Serine / metabolism
  • Substrate Specificity
  • Threonine / metabolism
  • Tyrosine / metabolism


  • Threonine
  • Tyrosine
  • Serine
  • Protein-Tyrosine Kinases
  • Protein-Serine-Threonine Kinases