Hartings H, Spilmont C, Lazzaroni N, Rossi V, Salamini F, Thompson R D, Motto M
Istituto Sperimentale per la Cerealicoltura, Sezione di Bergamo, Bergamo, Italy.
Mol Gen Genet. 1991 May;227(1):91-6. doi: 10.1007/BF00260712.
The two components of the Bg-rbg transposable element system of maize have been cloned. The Bg element, isolated from the mutable allele wx-m32:: Bg is inserted in the intron of the Waxy (Wx) gene between exons 12 and 13. The length of the element is of 4869 bp. Bg has 5 bp terminal inverted repeats, and generates upon insertion an 8 bp direct duplication of the target sequence. Both ends of the Bg element contain a 76 bp direct repeat adjacent to the terminal inverted repeats. The hexamer motif TATCGGC is here repeated several times in direct or inverse orientation. The rbg element was isolated from the mutable allele o2m(r) where it is located in the promoter region of the Opaque-2 (O2) gene. rbg is approximately 4.5 kb in length, has terminal inverted repeats identical to those of the Bg element, and is also flanked by an 8 bp direct duplication at the target site. Like Bg, rbg carries the 76 bp direct repeats. Restriction enzyme analysis reveals that, compared to Bg, the receptor element is distinguishable by small deletion and insertion events. Sequence data indicate that not more than 75% homology exists at the DNA level between the rbg element and the autonomous Bg element.
玉米的Bg-rbg转座子系统的两个组成部分已被克隆。从可变等位基因wx-m32::Bg中分离出的Bg元件插入到蜡质（Wx）基因第12和13外显子之间的内含子中。该元件长度为4869 bp。Bg具有5 bp的末端反向重复序列，插入时会产生8 bp的靶序列直接重复。Bg元件的两端在末端反向重复序列附近都含有一个76 bp的直接重复序列。六聚体基序TATCGGC在这里以正向或反向多次重复。rbg元件是从可变等位基因o2m(r)中分离出来的，它位于不透明2（O2）基因的启动子区域。rbg长度约为4.5 kb，具有与Bg元件相同的末端反向重复序列，并且在靶位点两侧也有一个8 bp的直接重复序列。与Bg一样，rbg也带有76 bp的直接重复序列。限制性内切酶分析表明，与Bg相比，受体元件可通过小的缺失和插入事件来区分。序列数据表明，rbg元件与自主的Bg元件在DNA水平上的同源性不超过75%。
