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Activation of a cellular tyrosine‐specific protein kinase by phosphorylation
Author(s) -
Swarup Ghanshyam,
Subrahmanyam Gosukonda
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80889-9
Subject(s) - mitogen activated protein kinase kinase , protein tyrosine phosphatase , biochemistry , phosphorylation , protein kinase a , map2k7 , microbiology and biotechnology , protein phosphorylation , chemistry , cyclin dependent kinase 2 , biology
A tyrosine‐specific protein kinase of M r 56 000 was purified over 200‐fold from rat spleen. Incubation of this kinase preparation with ATP and Mg 2+ results in about 10‐fold increase in the protein kinase activity. The activation of the kinase was unaffected in the presence of soyabean trypsin inhibitor. Polyacrylamide gel electrophoresis of the enzyme preparation after phosphorylation with ATP showed one phosphoprotein band of M r 56 000. During purification of this kinase a large decrease in enzyme activity was observed which could be prevented by adding 10 μM vanadate, as inhibitor of tyrosine‐specific protein phosphatases. These results suggest that the activation of the protein kinase by ATP is due to phosphorylation of the enzyme.