Rovira C, Edström J E
Department of Genetics, Lund University, Sweden.
Nucleic Acids Res. 1996 May 1;24(9):1662-8. doi: 10.1093/nar/24.9.1662.
Cp1 is a polymorphic short interspersed repeat (SINE) which is distributed over the whole genome of the dipteran Chironomus pallidivittatus, and is particularly abundant in the centromeres. It contains two different sequence modules, one of which, the B module, has a polymerase III internal control region (ICR) typical for tRNA genes (A and B box). Such sequence motifs are common in SINEs and assumed to function in RNA-mediated transposition. In the present case, however, several structural features speak for another role. An investigation of the transcription of the B module shows that it encodes a 99 nt RNA species in vivo, Cp1-RNA, terminating within the module. The transcription unit is likely to have evolved from a pre-tRNA gene and the transcript has sequence similarities to non-processed pre-tRNA. Most of the in vitro transcription is eliminated by deletion or substitution mutation of an upstream TATA box, present within the B module, as well as by changing either the A or B box. The properties of the transcript suggest that it does not have a role in transposition but may have some other function, perhaps in the centromere.
Cp1是一种多态性短散在重复序列（SINE），分布于双翅目昆虫苍白摇蚊的整个基因组中，在着丝粒中尤为丰富。它包含两个不同的序列模块，其中一个，即B模块，具有tRNA基因典型的聚合酶III内部控制区（ICR）（A盒和B盒）。这种序列基序在SINE中很常见，并被认为在RNA介导的转座中发挥作用。然而，在目前的情况下，几个结构特征表明其具有另一种作用。对B模块转录的研究表明，它在体内编码一种99个核苷酸的RNA分子，即Cp1-RNA，在模块内终止。转录单元可能是从一个前体tRNA基因进化而来的，并且转录本与未加工的前体tRNA具有序列相似性。B模块内存在的上游TATA盒的缺失或替换突变，以及A盒或B盒的改变，都消除了大部分体外转录。转录本的特性表明它在转座中没有作用，但可能有其他功能，也许在着丝粒中发挥作用。
