Science 1992 Feb 14;2555046:853-5. doi: 10.1126/science.1311128.

Tyrosyl phosphorylation and activation of MAP kinases by p56lck.

???displayArticle.abstract???
T cell signaling via the CD4 surface antigen is mediated by the associated tyrosyl protein kinase p56lck. The 42-kilodalton mitogen-activated protein (MAP) kinase (p42mapk) was tyrosyl-phosphorylated and activated after treatment of the murine T lymphoma cell line 171CD4+, which expresses CD4, with antibody to CD3. Treatment of the CD4-deficient cell line 171 with the same antibody did not result in phosphorylation or activation of p42mapk. Purified p56lck both tyrosyl-phosphorylated and stimulated the seryl-threonyl phosphotransferase activity of purified p44mpk, a MAP kinase isoform from sea star oocytes. A synthetic peptide modeled after the putative regulatory phosphorylation site in murine p42mapk (Tyr185) was phosphorylated by p56lck with a similar Vmax, but a fivefold lower Michaelis constant (Km) than a peptide containing the Tyr394 autophosphorylation site from p56lck. MAP kinases may participate in protein kinase cascades that link Src family protein-tyrosyl kinases to seryl-threonyl kinases such as those encoded by rsk and raf, which are putative substrates of MAP kinases.

???displayArticle.pubmedLink??? 1311128
???displayArticle.link??? Science
???displayArticle.grants??? [+]

Genes referenced: LOC100887844 LOC115919758 LOC115919910 LOC574936 LOC586799 LOC591473 LOC594566 mos