title: Evidence of tyrosine kinase activity in the protozoan parasite Trypanosoma brucei.
abstract: Phosphorylation of proteins at tyrosine is an important mechanism for regulating cell growth and proliferation in metazoan organisms. In this report, we have demonstrated that Trypanosoma brucei, a protozoan parasite, possesses a tyrosine kinase that plays a role in regulation of proliferation of this protozoan. Genistein, a tyrosine kinase inhibitor, prevented multiplication of the parasite. An in vitro kinase assay demonstrated the presence of a kinase capable of phosphorylating an exogenous substrate at tyrosine, and genistein was able to reduce trypanosome-mediated phosphorylation of this substrate. An alkali digestion of 32P-labeled trypanosome proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated several proteins phosphorylated at tyrosine. These results indicate that T. brucei has a tyrosine kinase that is involved in proliferation or growth regulation of the parasite and provide further evidence for the possibility of growth factor regulation and signal transduction in trypanosomes.
authors.affiliation: Department of Veterinary Pathobiology, University of Illinois, Urbana 61801.
authors.forename: E
authors.initials: E
authors.lastname: Wheeler-Alm
authors.forename: S Z
authors.initials: SZ
authors.lastname: Shapiro
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D002461:Cell Line, Transformed; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism; D051381:Rats; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000201:enzymology*
chemical_list: D007529:Isoflavones; D015800:Protozoan Proteins; D010769:Phosphothreonine; D010768:Phosphoserine; D019833:Genistein; D011505:Protein-Tyrosine Kinases