ROLE OF XPO, LOCALIZED ZINC FINGER GENE, IN XENOPUS ANTERIOR-POSTERIOR AXIS FORM

在原肠胚形成期间建立的前后轴需要2 主要事件：第一，背中胚层获得极性， 第二，由背中胚层诱导外胚层。我们感兴趣 在理解形成的分子基础上， 前-后轴和特征基因，XPO （Xenopus-posterior），可能参与了这一过程。XPO cDNA 克隆（4.2 KB）已测序，除了18个 与所含锌指具有>75%同源性的氨基酸序列 在GAG内，逆转录病毒的小核酸结合蛋白。 此外，推导的蛋白质的N-末端部分含有一个 不是典型“亮氨酸拉链”的七肽重复序列。将mrna 存在于早期原肠胚中，在神经胚形成期间达到高峰， 消失在被吃掉的尾芽阶段在第11阶段， 高度定位于后中胚层和外胚层， 存在于前外胚层的成分。在第13阶段， 在邻近神经节的前外胚层中也观察到 板在前额叶皮层也观察到少量转录本 外胚层在邻近神经板的区域。在动物的外胚层中 诱导试验表明，XPO可被碱性FGF和XTC诱导 因子

The anterior-posterior axis, established during gastrulation, requires 2 major events: first, the acquisition of polarity by dorsal mesoderm and second, the induction of ectoderm by the dorsal mesoderm. We are interested in understanding the molecular basis of the formation of the anterior-posterior axis and have characterized a gene, XPO (Xenopus-posterior), which may be involved in this process. The XPO cDNA clone (4.2 KB) has been sequenced and is completely unique except for an 18 amino acid sequence that is >75% homologous to the zinc finger contained within GAG, the small nucleic acid binding protein of retroviruses. Additionally, the N-terminal portion of the deduced protein contains a heptad repeat which is not a classical "leucine zipper". The mRNA is present in early gastrulating embryos, reaches its peak during neurulation, and disappears by the ate tailbud stage. At stage 11 the transcript appears to be highly localized in osterior mesoderm and ectoderm with a small component present in the anterior ectoderm. At stage 13, the transcript was also observed in the anterior ectoderm in a region adjacent to the neural plate. A small amount of transcript was also observed in the anterior ectoderm in a region adjacent to the neural plate. In an animal ectoderm induction assay, XPO has been shown to be induced by both basic FGF and XTC factor.