Mosquera L, Forristall C, Zhou Y, King M L
Department of Cell Biology and Anatomy (R-124), University of Miami School of Medicine, FL 33101.
Development. 1993 Jan;117(1):377-86. doi: 10.1242/dev.117.1.377.
mRNAs concentrated in specific regions of the oocyte have been found to encode determinants that specify cell fate. We show that an intermediate filament fraction isolated from Xenopus stage VI oocytes specifically contains, in addition to Vg1 RNA, a new localized mRNA, Xcat-2. Like Vg1, Xcat-2 is found in the vegetal cortical region, is inherited by the vegetal blasomeres during development, and is degraded very early in development. Sequence analysis suggests that Xcat-2 encodes a protein that belongs to the CCHC RNA-binding family of zinc finger proteins. Interestingly, the closest known relative to Xcat-2 in this family is nanos, an RNA localized to the posterior pole of the Drosophila oocyte whose protein product suppresses the translation of the transcription factor hunchback. The localized and maternally restricted expression of Xcat-2 RNA suggests a role for its protein in setting up regional differences in gene expression that occur early in development.
已发现集中在卵母细胞特定区域的信使核糖核酸（mRNAs）可编码决定细胞命运的决定因素。我们发现，从非洲爪蟾第六期卵母细胞中分离出的中间丝组分，除了Vg1核糖核酸外，还特异性地含有一种新的定位信使核糖核酸Xcat-2。与Vg1一样，Xcat-2存在于植物皮质区域，在发育过程中由植物卵裂球继承，并在发育早期就被降解。序列分析表明，Xcat-2编码一种属于锌指蛋白CCHC核糖核酸结合家族的蛋白质。有趣的是，在这个家族中，与Xcat-2最接近的已知亲属是nanos，一种定位在果蝇卵母细胞后极的核糖核酸，其蛋白质产物可抑制转录因子驼背蛋白的翻译。Xcat-2核糖核酸的定位和母系限制表达表明其蛋白质在建立发育早期出现的基因表达区域差异中发挥作用。
