Four tyrosine-protein kinases that reacted with antibodies specific to p62c-yes, p60c-src, p60c-src, and p59fyn, respectively, were solubilized from a rat brain particulate fraction and separated by casein-Toyopearl column chromatography. Possible p59fyn, with a pI of 6.5, was purified 490-fold as a single 69-kDa protein band on SDS-PAGE. The purified enzyme contained almost no phosphotyrosine residues but was autophosphorylated with Mg2+-·ATP exclusively at tyrosine residues, with a concomitant increase in the kinase activity toward tyrosine-glutamate (1 : 4) copolymers. The rate of the copolymer phosphorylation was proportional to the square of the enzyme concentration, suggesting activation through intermolecular catalysis. In the presence of Mn2+, however, the reaction showed a firstorder dependence on the enzyme concentration.
|Number of pages||4|
|Journal||Journal of biochemistry|
|Publication status||Published - 1992 Dec|
ASJC Scopus subject areas
- Molecular Biology