Developmental regulation of pp44/46, tyrosine-phosphorylated proteins associated with tyrosine/serine kinase activity in Trypanosoma brucei

Mol Biochem Parasitol. 1994 Jan;63(1):69-78. doi: 10.1016/0166-6851(94)90009-4.


The pattern of tyrosine-phosphorylated proteins is developmentally regulated in Trypanosoma brucei. To examine the function and regulation of these tyrosine-phosphorylated molecules, monoclonal antibodies were generated using purified tyrosine-phosphorylated proteins as immunogens. Two monoclonal antibodies were obtained. Both react with a set of proteins at 44-46 kDa, collectively referred to as pp44/46, that are phosphorylated on serine and tyrosine. Differentiation of the parasite from slender bloodforms to procyclic forms was accompanied by increased abundance and tyrosine-phosphorylation of pp44/46. The monoclonal antibodies immunoprecipitated protein kinase activity capable of phosphorylating pp44/46 on serine and tyrosine, and myelin basic protein on serine. The data indicate that the prominent tyrosine-phosphorylated proteins induced upon differentiation are either themselves protein kinases or that they are associated with protein kinases.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Calcium-Calmodulin-Dependent Protein Kinases / immunology
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism*
  • Protein-Tyrosine Kinases / metabolism*
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / immunology
  • Protozoan Proteins / metabolism*
  • Serine / chemistry
  • Trypanosoma brucei brucei / growth & development
  • Trypanosoma brucei brucei / metabolism*
  • Tyrosine / chemistry


  • Antibodies, Monoclonal
  • Protozoan Proteins
  • Tyrosine
  • Serine
  • Protein-Tyrosine Kinases
  • Protein-Serine-Threonine Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases