Zorn A M, Grow M, Patterson K D, Ebersole T A, Chen Q, Artzt K, Krieg P A
Center for Developmental Biology and Genetics Institute, Department of Zoology, University of Texas at Austin, 78712, USA.
Gene. 1997 Apr 1;188(2):199-206. doi: 10.1016/s0378-1119(96)00795-0.
Mutations in the mouse quaking locus can result in two different types of developmental phenotypes: (1) a deficiency of myelin in the central nervous system that is accompanied by a characteristic tremor, or (2) embryonic lethality around day 9 of gestation. A quaking candidate gene (qkI) that encodes a KH motif protein has recently been identified. We have isolated and characterized cDNAs encoding the Xenopus quaking homologue (Xqua) and also assembled an almost complete human quaking sequence from expressed sequence tags. Sequence comparisons show that the amphibian and mammalian quaking transcripts exhibit striking conservation, both within the coding region and, unexpectedly, in the 3' UTR. Two Xqua transcripts 5 kb and 5.5 kb in length are differentially expressed in the Xenopus embryo, with the 5 kb transcript being detected as early as the gastrula stage of development. Using an in vitro assay, we have demonstrated RNA-binding activity for quaking protein encoded by the 5 kb transcript. Overall, the high sequence conservation of quaking sequences suggests an important conserved function in vertebrate development, probably in the regulation of RNA metabolism.
（1）中枢神经系统髓鞘缺乏，并伴有特征性震颤；或（2）妊娠第9天左右胚胎致死。最近已鉴定出一个编码KH基序蛋白的震颤候选基因（qkI）。我们已分离并鉴定了编码非洲爪蟾震颤同源物（Xqua）的cDNA，并从表达序列标签中组装了几乎完整的人类震颤序列。序列比较表明，两栖动物和哺乳动物的震颤转录本在编码区域以及意外地在3'UTR内都表现出惊人的保守性。两种长度分别为5 kb和5.5 kb的Xqua转录本在非洲爪蟾胚胎中差异表达，5 kb的转录本早在发育的原肠胚阶段就可检测到。使用体外试验，我们已证明由5 kb转录本编码的震颤蛋白具有RNA结合活性。总体而言，震颤序列的高度保守性表明其在脊椎动物发育中具有重要的保守功能，可能在RNA代谢调节中发挥作用。
