Fawcett D H, Lister C K, Kellett E, Finnegan D J
Cell. 1986 Dec 26;47(6):1007-15. doi: 10.1016/0092-8674(86)90815-9.
I-R hybrid dysgenesis in D. melanogaster is controlled by transposable elements known as I factors. We have determined the base sequences of one complete I factor and the ends of six others. The ends of these elements are highly conserved and are flanked by target site duplications varying in length from 10-14 bp. There are no terminal repeats, and the 3' end of one strand is A-rich, having 4-7 tandem repeats of the sequence TAA. This sequence organization is similar to that of mammalian LINEs, or L1 elements. The complete I factor sequence contains two long open reading frames, ORF1 and ORF2, of 1278 and 3258 bp. ORF1 encodes a possible nucleic acid-binding protein, and part of the amino acid sequence of ORF2 is similar to that of viral reverse transcriptases and polypeptides encoded by L1 elements. These results suggest that I factors transpose by reverse transcription of a full-length RNA.
黑腹果蝇中的I-R杂种不育现象由被称为I因子的转座元件控制。我们已经确定了一个完整I因子的碱基序列以及其他六个I因子的末端序列。这些元件的末端高度保守，两侧是长度从10到14个碱基对不等的靶位点重复序列。没有末端重复序列，一条链的3'端富含A，具有4至7个TAA序列的串联重复。这种序列组织类似于哺乳动物的长散在核元件（LINEs）或L1元件。完整的I因子序列包含两个长开放阅读框，即1278个碱基对的ORF1和3258个碱基对的ORF2。ORF1编码一种可能的核酸结合蛋白，ORF2的部分氨基酸序列与病毒逆转录酶以及L1元件编码的多肽的氨基酸序列相似。这些结果表明I因子通过全长RNA的逆转录进行转座。
