Unexpected effects of FERM domain mutations on catalytic activity of Jak3: structural implication for Janus kinases

Mol Cell. 2001 Nov;8(5):959-69. doi: 10.1016/s1097-2765(01)00398-7.


Janus kinases comprise carboxyterminal kinase, pseudokinase, SH2-like, and N-terminal FERM domains. We identified three patient-derived mutations in the FERM domain of Jak3 and investigated the functional consequences of these mutations. These mutations inhibited receptor binding and also abrogated kinase activity, suggesting interactions between the FERM and kinase domains. In fact, the domains were found to physically associate, and coexpression of the FERM domain enhanced activity of the isolated kinase domain. Conversely, staurosporine, which alters kinase domain structure, disrupted receptor binding, even though the catalytic activity of Jak3 is dispensable for receptor binding. Thus, the Jak FERM domain appears to have two critical functions: receptor interaction and maintenance of kinase integrity.

MeSH terms

  • Adenosine Triphosphate / analogs & derivatives
  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Catalysis
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Interleukin Receptor Common gamma Subunit
  • Janus Kinase 3
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation
  • Protein Structure, Tertiary
  • Protein-Tyrosine Kinases / chemistry
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism*
  • Pyrimidines / pharmacology
  • Receptors, Interleukin-7 / genetics
  • Receptors, Interleukin-7 / metabolism
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Staurosporine / pharmacology
  • src-Family Kinases / antagonists & inhibitors


  • AG 1879
  • Enzyme Inhibitors
  • IL2RG protein, human
  • Interleukin Receptor Common gamma Subunit
  • Pyrimidines
  • Receptors, Interleukin-7
  • Recombinant Fusion Proteins
  • Adenosine Triphosphate
  • Protein-Tyrosine Kinases
  • JAK3 protein, human
  • Janus Kinase 3
  • src-Family Kinases
  • Staurosporine