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 在相同的细胞上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 基因组。 我们发现了潜伏的细胞质转录 被这种配体激活的因子。 那些潜在的细胞质 蛋白质，称为STAT蛋白的信号转导和激活剂， 转录前在细胞质中酪氨酸磷酸化 转移到细胞核来指导转录。 他们第一 在用IFN-α或IFN-γ处理的细胞中发现。 在这 建议我们描述实验来定义一个功能域 这些蛋白质，STAT 91，和激酶的功能结构域 (Jak1和Jak 2），已被证明参与STAT 活化途径 今后工作的一个最重要的重点是 发现这个家族中的其他蛋白质， 其他配体。 因为编码目前已知的STAT的基因 已经发现蛋白质有许多（20）外显子，我们将研究STAT 不同小鼠组织和细胞中的mRNAs在各种不同的 寻找不同剪接的STAT mRNA的方法， 不同的配体依赖途径。 几个新发现的STAT 胸腺中存在的具有mRNA的蛋白质家族成员也 描述了具有高度同源性但明显不同于 已经描述的STAT 91和113蛋白。 表征 这些蛋白质，特别注意其可能的酪氨酸 对其他配体的磷酸化反应是这一过程的重要组成部分。 提议 最后，计划合作研究这三个- STAT蛋白的重要结构域的三维结构和 与它们相互作用的激酶。

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.