Bourbon H, Michot B, Hassouna N, Feliu J, Bachellerie J P
Centre de Recherche de Biochimie et de Génétique Cellulaires du CNRS, Toulouse, France.
DNA. 1988 Apr;7(3):181-91. doi: 10.1089/dna.1988.7.181.
We report the sequence of the 4006-nucleotide 5' external transcribed spacer (5'ETS) of the mouse ribosomal primary transcript. These data complete the sequence of the 13.4-kb mouse rRNA gene, thus providing a mammalian rRNA gene structure, in addition to yeast and Xenopus. The mouse 5'ETS displays a highly biased base content (very high in GC and particularly low in A), closely similar to the other transcribed spacers of the mouse ribosomal gene. This region seems to have accumulated sequence variation relatively rapidly during vertebrate evolution, with the possible insertion in rodents of sequences structurally similar to retroposons. About half the length of the mouse 5'ETS can fold into a giant and highly stable secondary structure, which is probably evolutionarily conserved in mammals and which could play an important role in the higher-order organization of mammalian pre-ribosomes.
我们报道了小鼠核糖体初级转录本4006个核苷酸的5′外部转录间隔区（5′ETS）的序列。这些数据完善了13.4kb小鼠rRNA基因的序列，从而除了酵母和非洲爪蟾之外，提供了一种哺乳动物rRNA基因结构。小鼠5′ETS的碱基含量存在高度偏差（GC含量非常高，A含量特别低），与小鼠核糖体基因的其他转录间隔区极为相似。在脊椎动物进化过程中，该区域似乎相对快速地积累了序列变异，在啮齿动物中可能插入了结构上类似于反转录转座子的序列。小鼠5′ETS长度的大约一半能够折叠成一个巨大且高度稳定的二级结构，该结构可能在哺乳动物中是进化保守的，并且可能在哺乳动物前核糖体的高级组装中发挥重要作用。
