Stable interdomain interaction within the cytoplasmic domain of CD45 increases enzyme stability

Biochem Biophys Res Commun. 2000 May 10;271(2):292-8. doi: 10.1006/bbrc.2000.2623.


CD45 is a leukocyte-specific, two domain transmembrane tyrosine phosphatase. Co-purification of a recombinant protein containing the first phosphatase domain of CD45 (6His-D1) with a recombinant protein containing the second phosphatase domain (GST-D2) from E. coli indicated a stable interaction which resulted in increased stability of the active phosphatase domain present in 6His-D1. This interaction was not dependent on the acidic region unique to CD45 domain 2, but was affected by a destabilizing point mutation (Q1180G) in GST-D2. CD45 domain 2 enhanced phosphatase activity of the first domain in the full length cytoplasmic domain protein, whereas a chimeric protein with the SH2 domain of p56(lck) in place of the CD45 C-terminal region did not. Thus the C-terminal domain of CD45 associates with the N-terminal domain and this stabilizes the active phosphatase domain. A single destabilizing point mutation in the second domain is sufficient to attenuate this effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catalysis
  • Cytoplasm / chemistry*
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Stability
  • Glutathione Transferase / metabolism
  • Kinetics
  • Leukocyte Common Antigens / chemistry*
  • Leukocyte Common Antigens / genetics
  • Mice
  • Mutation
  • Phosphoric Monoester Hydrolases / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / chemistry
  • Recombination, Genetic
  • Signal Transduction
  • Temperature


  • Recombinant Fusion Proteins
  • Glutathione Transferase
  • Phosphoric Monoester Hydrolases
  • Leukocyte Common Antigens