Takishima K, Griswold-Prenner I, Ingebritsen T, Rosner M R
Ben May Institute, Chicago, IL.
Proc Natl Acad Sci U S A. 1991 Mar 15;88(6):2520-4. doi: 10.1073/pnas.88.6.2520.
The epidermal growth factor (EGF) receptor is both an activator and a target of growth factor-stimulated kinases involved in cellular signaling. Threonine-669 (T669) of the EGF receptor is phosphorylated in response to a wide variety of growth-modulating agents. MAP kinase is similarly phosphorylated as well as stimulated by growth activators, including EGF. To determine whether a MAP-type kinase is responsible for T669 kinase activity in EGF-stimulated 3T3-L1 cells, we partially purified and characterized the T669 peptide kinase. The results indicate that a MAP kinase phosphorylates the T669 peptide and raise the possibility that this enzyme may participate in a feedback loop, being activated by the EGF receptor and in turn phosphorylating the receptor.
表皮生长因子（EGF）受体既是参与细胞信号传导的生长因子刺激激酶的激活剂，也是其作用靶点。EGF受体的苏氨酸-669（T669）会因多种生长调节因子而发生磷酸化。丝裂原活化蛋白激酶（MAP激酶）同样会被包括EGF在内的生长激活剂磷酸化并激活。为了确定在EGF刺激的3T3-L1细胞中，是否有MAP型激酶负责T669激酶活性，我们对T669肽激酶进行了部分纯化和特性鉴定。结果表明，一种MAP激酶可使T669肽发生磷酸化，这增加了该酶可能参与反馈回路的可能性，即被EGF受体激活，进而使该受体发生磷酸化。
