SPECIFICITY AND DIMERIZATION IN MAP KINASE INTERACTIONS

MAP激酶是一个大家族的多效性蛋白激酶，其传递信号导致不同的调节事件，包括增殖、分化功能和对环境损伤的反应。MAP激酶ERK 1和ERK 2响应导致生长和分化的信号。相关的MAP激酶p38和其他同系物参与应激反应。MAP激酶家族成员各自具有与底物和上游活化剂的独特相互作用星座，以确保可靠的信号传导。我们先前确定了ERK 2和p38的低活性形式的结构，以及ERK 2的活性形式。我们将继续我们的结构研究这个家庭，并将分析MAP激酶与肽和全长蛋白质的相互作用，以确定MAP激酶ERK 2和p38对转录因子和蛋白激酶底物的选择性相互作用的结构基础。我们发现ERK 2在磷酸化时发生二聚化，并且活性ERK 2的结构显示为二聚体。许多MAP激酶底物是二聚体。二聚化在信号传导过程中是普遍存在的，并且可以通过改善对正确底物的选择性而显著有助于正确的信号靶向。在本研究中，我们将对活性二聚ERK 2和活性二聚缺陷突变体进行动力学分析，以确定二聚对转录因子底物活性的影响。

MAP kinases are a large family of pleiotropic protein kinases that transduce signals leading to diverse regulatory events, including proliferation, differentiated functions, and responses to environmental insult. The MAP kinases ERK1 and ERK2 respond to signals leading to growth and differentiation. The related MAP kinase p38 and other homologs are involved in stress responses. MAP kinase family members each have a unique constellation of interactions with substrates and upstream activators that assure faithful signaling. We previously determined the structures of the low activity forms of ERK2 and p38, and the active form of ERK2. We will continue our structural studies of this family, and will analyze the interactions of MAP kinases with peptides and full-length proteins to determine the structural basis for selective interactions of the MAP kinases ERK2 and p38 toward transcription factors and protein kinase substrates. We discovered that ERK2 dimerizes when phosphorylated, and the structure of active ERK2 revealed a dimer. Many MAP kinase substrates are dimers. Dimerization is ubiquitous in signaling processes, and may contribute significantly to correct targeting of signals by improving selectivity for the correct substrates. In this study, we will carry out kinetic analysis of active dimeric ERK2 and an active dimerization- deficient mutant to determine the effect of dimerization on the activity toward transcription factor substrates.