Structural Studies of the Pseudokinase Domain of Jak2

Janus激酶(JAKs)是非受体蛋白酪氨酸激酶家族的成员，是蛋白酪氨酸激酶的重要组成部分。 免疫系统细胞和造血细胞中的信号通路。JAK与 细胞因子受体的胞质结构域，在细胞因子介导的受体二聚时，经历自磷酸化 对酪氨酸残基，这刺激他们的酪氨酸激酶活性。激活的JAKS 磷酸化的STATs(信号转导和转录激活子)，它转移到细胞核和 作为转录激活剂。JAK家族有四个哺乳动物成员(JAK1-3和TYK2) 它们具有四个共同的结构域：N-末端FERM结构域、SH2样结构域、伪激酶 结构域，以及酪氨酸激酶结构域。大量的生化数据，以及功能获得突变 导致骨髓增殖性疾病/癌症，已牵涉到JAKS的假激酶结构域对 维持较低的基础水平的酪氨酸激酶活性。这项建议的目标是了解 假激酶结构域负性调节酪氨酸激酶的结构/分子机制 JAK2的活性。为了实现这一目标，将使用x射线结晶学来确定三维 假激活区和串联假激活区和酪氨酸激酶区的结构。

Janus kinases (Jaks), members of the non-receptor protein tyrosine kinase family, are key components of signaling pathways in cells of the immune system and in hematopoietic cells. Jaks are associated with the cytoplasmic domains of cytokine receptors and, upon cytokine-mediated receptor dimerization, undergo transautophosphorylation on tyrosine residues, which stimulates their tyrosine kinase activity. Activated Jaks phosphorylate STATs (signal transducers and activators of transcription), which translocate to the nucleus and serve as transcriptional activators. There are four mammalian members of the Jak family (Jak1-3 and Tyk2) which possess four domains in common: an N-terminal FERM domain, an SH2-like domain, a pseudokinase domain, and a tyrosine kinase domain. Extensive biochemical data, as well as gain-of-function mutations that cause myeloproliferative diseases/cancers, have implicated the pseudokinase domain of Jaks as crucial for maintaining a low basal level of tyrosine kinase activity. The goal of this proposal is to understand the structural/molecular mechanisms by which the pseudokinase domain negatively regulates the tyrosine kinase activity of Jak2. To achieve this goal, x-ray crystallography will be employed to determine the three-dimensional structures of the pseudokinase domain and the tandem pseudokinase and tyrosine kinase domains.