Friedberg F, Saunders A A, Rhoads A R
Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, Washington, DC, USA.
Mol Biol Rep. 2003 Sep;30(3):193-8. doi: 10.1023/a:1024951015607.
Three separate calmodulin (CaM) genes (I, II and III) encoding an identical CaM protein but differing in the 5'- and 3'-untranslated regions of each of the three mRNAs are present and highly conserved in all mammals (so far examined). Primers complementary to the 3'- untranslated region (3'UTR) of each of the three mRNAs occurring in human, rat and mouse were synthesized and used to amplify regions of the 3'UTR from genomic DNA isolated from cetaceans, specifically from the bottled-nosed dolphin (Tursiops truncates), the pygmy sperm whale (Kogia breviceps) and the humpback whale (Megaptera novaeangliae). Using several primers and PCR conditions, the three CaM genes were identified in all three species by this method with one exception. The sequenced regions of the 3'UTRs of the three genes of the cetaceans exhibited a high percentage identity when compared to the corresponding regions of these three CaM mRNAs isolated from humans (85-96%). These partial sequences of the 3'UTR regions and the corresponding regions for humans, rats and mice that were available from the database were aligned and a phylogenetic tree was constructed. The three CaM genes from all species showed a close phylogenetic relationship based on these 3'UTR sequences. Such high conservation of the 3'UTRs suggests a specialized and significant function for this region in mammals.
在所有哺乳动物（迄今为止已检测的）中，存在三个单独的钙调蛋白（CaM）基因（I、II和III），它们编码相同的CaM蛋白，但三种mRNA各自的5'非翻译区和3'非翻译区有所不同，且高度保守。合成了与人类、大鼠和小鼠中出现的三种mRNA的3'非翻译区（3'UTR）互补的引物，并用于从鲸类动物（具体为宽吻海豚（Tursiops truncates）、侏虎鲸（Kogia breviceps）和座头鲸（Megaptera novaeangliae））分离的基因组DNA中扩增3'UTR区域。使用多种引物和PCR条件，通过这种方法在所有三个物种中都鉴定出了这三个CaM基因，但有一个例外。与从人类分离的这三种CaM mRNA的相应区域相比，鲸类动物三个基因的3'UTR的测序区域显示出很高的百分比同一性（85 - 96%）。将3'UTR区域的这些部分序列与数据库中可获得的人类、大鼠和小鼠的相应区域进行比对，并构建了系统发育树。基于这些3'UTR序列，所有物种的三个CaM基因显示出密切的系统发育关系。3'UTR的这种高度保守性表明该区域在哺乳动物中具有特殊且重要的功能。
