Cytoplasmic Retention as a Regulatory Mechanism in Embryogenesis

小行星9319178 许多核蛋白的功能是通过选择性核定位来调节的。 非洲爪蟾核因子7（xnf7）是一个新的锌指基因家族的成员，其成员主要包括转录因子和原癌基因。 Xnf7首先在卵母细胞核中被检测到，并保留在细胞质中，直到发育的中期囊胚阶段，当它重新进入细胞核。 最近的证据表明，xnf7中的一个22个氨基酸序列称为胞质滞留结构域（CRD）是必需的细胞质滞留前中期囊胚阶段和磷酸化的蛋白质内的两个位点是必要的适当的CRD功能。 Etkin博士的实验室已经表明，xnf7通过一种锚机制保留在细胞质中，这种机制很可能涉及到与胞浆锚蛋白的连接。 该项目中测试的假设是磷酸化诱导xnf7的结构变化，导致CRD序列与锚蛋白结合。 Etkin博士将通过实现以下具体目标来验证这一假设：（1）他将进一步确定磷酸化在细胞质中保留xnf7中的作用。 (2)他将分析和鉴定与CRD序列相互作用的蛋白质，并在xnf7的细胞质保留中发挥作用，并将克隆这些蛋白质的cDNA。 除了深入了解两栖动物发育过程中的一个重要调控过程外，对xnf7选择性核定位机制的分析将为理解其他系统中的这种现象提供必要的信息。 ***

9319178 Etkin The function of many nuclear proteins is regulated by selective nuclear localization. Xenopus nuclear factor 7 (xnf7), a putative transcription factor, is a member of a novel zinc finger gene family whose members consist primarily of transcription factors and protooncogenes. Xnf7 is first detected in the oocyte nucleus and is retained in the cytoplasm until the mid blastula stage of development when it reenters the nucleus. Recent evidence showed that a 22 amino acid sequence in xnf7 called the cytoplasmic retention domain (CRD) is required for cytoplasmic retention prior to the mid blastula stage and that phosphorylation of two sites within the protein is necessary for proper CRD function. Dr. Etkin's laboratory has shown that xnf7 is retained in the cytoplasm through an anchor mechanism most likely involving the tethering to a ctyoplasmic anchor protein. The hypothesis being tested in this project is that phosphorylation induces a structural change in xnf7 resulting in the binding of the CRD sequence to an anchor protein. Dr. Etkin will test this hypothesis by accomplishing the following specific aims: (1) He will further determine the role of phosphorylation in the retention of xnf7 in the cytoplasm. (2) He will analyze and identify the proteins that interact with the CRD sequence and function in cytoplasmic retention of xnf7 and will clone the cDNAs for these proteins. In addition to gaining an insight into an important regulatory process during amphibian development, the analysis of the mechanism of selective nuclear localization of xnf7 will provide information necessary to understand this phenomenon in other systems. ***