GENE ACTIVATION BY POLYPEPTIDES--CELL SURFACE TO NUCLEUS

不同的多肽配体可以与特定的细胞表面受体结合 并启动不同的细胞内事件，包括 立即(不需要蛋白质合成)激活不同的 一组基因。我们发现了潜在的细胞质转录 由这类配体激活的因子。那些潜伏的细胞质 蛋白质，称为STAT蛋白，用于信号转导和激活 转录在细胞质中的酪氨酸被磷酸化之前 移位到细胞核以指导转录。他们是第一个 在用干扰素-α或干扰素-γ处理的细胞中发现。在这 建议我们描述定义一个的功能域的实验 在这些蛋白质中，STAT 91和激酶的功能结构域 (JAK1和JAK2)已被证明参与状态 激活途径。未来工作的一个最重要的主旨将是 发现同一家族中的其他蛋白质，它们服务于 其他配体。因为编码目前已知状态的基因 已经发现蛋白质有许多(20)个外显子，我们将研究这一状态 在不同的小鼠组织和不同处理的细胞中的mRNA 搜索可能在中发挥作用的不同剪接的STAT mRNA的方法 不同的配体依赖途径。几种新发现的状态 存在于胸腺中的具有mRNAs的蛋白质家族成员也 描述了与之高度同源但又截然不同的 已经描述的STAT 91和113蛋白。特征描述 这些蛋白质特别注意它们可能存在的酪氨酸 对其他配体反应的磷酸化是这一过程的重要部分。 求婚。最后，计划合作研究以下三个方面： STAT蛋白重要结构域的空间结构和 与之相互作用的蛋白水解酶。

Different polypeptide ligands can bind to specific cell surface receptors on the same cell and initiate different intracellular events including the immediate (non-protein synthesis requiring) activation of different sets of genes. We have discovered latent cytoplasmic transcription factors that are activated by such ligands. Those latent cytoplasmic proteins, termed STAT proteins for signal transducers and activators of transcription are phosphorylated on tyrosine in the cytoplasm before translocating to the nucleus to direct transcription. They were first discovered in cells treated with IFN-alpha or IFN-gamma. In this proposal we describe experiments to define the functional domains of one of these proteins, STAT 91, and the functional domains of the kinases (Jak1 and Jak2) that have been shown to be involved in the STAT activation pathway. A most important thrust of future work will be discover other proteins in this same family that serve in response to other ligands. Because the genes encoding the presently known STAT proteins have been found to have many (20) exons we will study the STAT mRNAs in different mouse tissues and in cells treated in a variety of ways to search for differently spliced STAT mRNAs that might function in different ligand-dependent pathways. Several newly discovered STAT protein family members with mRNAs that are present in the thymus are also described that have high homology to but are distinctly different from the already described STAT 91 and 113 proteins. Characterization of these proteins with particular attention to their possible tyrosine phosphorylation in response to other ligands is an important part of this proposal. Finally, collaboration is planned to study the three- dimensional structure of important domains of the STAT proteins and the kinases with which they interact.