The Journal of Biochemistry
Online ISSN : 1756-2651
Print ISSN : 0021-924X
Purification and Characterization of a Possible Protooncogene fyn Product, p59fyn, from a Rat Brain Particulate Fraction
Takahiro MiyauchiMasahiro ArikiHirofumi UsuiKentaro SembaYumiko MatsuzawaTadashi YamamotoKumao ToyoshimaMasao Takeda
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1992 Volume 112 Issue 6 Pages 729-732


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 59-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.

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