• Biomedical Science Letters
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• v.2 no.1
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• pp.21-30
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• 1996

MAP kinases are a family of serine/threonine specific protein kinases becoming activated in response to different proliferative stimuli by phosphorylation at both threonine and tyrosine residue. Present study shows that MAP kinase was purified from P388 murine leukema cells by SP sephadex C-50, phenyl superose and Mono Q column chromatography and identified with anti-ERKl antibody by western blotting. Immnublotting analysis to the crude extract of P388 cell lysate shows 44 kD and other minor bands but partial purified fraction eluted from phenyl supherose column have 44kD and 66 kD isoform. Subcloned GST-fusion protein from N-terminal of $p56^{kk}$ was tested as a substrate for MAP kinase phosphorylation. It was showed that the wild type and mutant forms(S42A) were fully phosporylated by purified MAP kinase fraction as com-pare with the other mutant form(S59A). This finding suggest that those GST-fusion proteins may be used as substrate for the in vitro test of MAP kinase.