Georgieva S G, Mizrokhi L Iu, Krichevskaia A A, Il'in Iu V
Genetika. 1988 Aug;24(8):1353-63.
Two polyadenylated transcripts of the jockey are detected at different stages of Drosophila melanogaster ontogenesis and in the cell culture. They have the same length as complete and deleted copies of jockey and correspond to the DNA strand containing open reading frames coding for polypeptides which are homologous to retroviral RNA-(DNA)-binding proteins and to their reverse transcriptases. The results of the experiments, where transcription was inhibited with alpha-amanitin in vivo, indicate that jockey is transcribed by RNA polymerase II. The analysis of expression of CAT constructions made on the basis of jockey, and the detection of a fixed site for transcription initiation in jockey genomic and transfected copies have shown that jockey transcription is controlled by an internal promoter located not farther than 12 nucleotides from the beginning of the element. Such an inward location of the promoter allows it to be preserved in replication via reverse transcription and accounts for the distribution of jockey and probably other LINEs throughout the genome. This is the case of the first internal promoter described for RNA polymerase II. The comparison of starting sequences of LINEs in Drosophila makes it possible to detect core sequences of such a promoter.
在黑腹果蝇个体发育的不同阶段以及细胞培养中检测到了“赛马”元件的两种多聚腺苷酸化转录本。它们的长度与“赛马”元件的完整拷贝和缺失拷贝相同，并且与包含编码与逆转录病毒RNA-（DNA）结合蛋白及其逆转录酶同源的多肽的开放阅读框的DNA链相对应。体内用α-鹅膏蕈碱抑制转录的实验结果表明，“赛马”元件由RNA聚合酶II转录。对基于“赛马”元件构建的CAT结构的表达分析以及在“赛马”元件基因组拷贝和转染拷贝中检测到转录起始固定位点，表明“赛马”元件的转录受一个内部启动子控制，该启动子距离元件起始处不超过12个核苷酸。启动子的这种向内定位使其能够通过逆转录在复制过程中得以保留，并解释了“赛马”元件以及可能其他长散在核元件在整个基因组中的分布情况。这是首次描述的RNA聚合酶II内部启动子的情况。对果蝇中长散在核元件起始序列的比较使得检测这种启动子的核心序列成为可能。
