Institut für Genetik, Universität zu Köln, D-5000 Köln 41, FRG.
EMBO J. 1987 Jun;6(6):1555-63. doi: 10.1002/j.1460-2075.1987.tb02400.x.
Transcripts of various sizes hybridize to the transposable element Ac of Zea mays in most maize lines. A 3.5-kb mRNA with an abundance of 1-3 x 10 of the poly(A) RNA, however, is found exclusively in those lines that carry an active Ac. Plants with two Ac elements contain slightly more 3.5-kb Ac transcript than those with only one Ac. Overlapping cDNA clones spanning most of the message have been isolated and sequenced. The 5'-end of the transcript was determined by Northern hybridization and S1 mapping. It starts at several sites over a distance of nearly 100 bases, contains an AUG-free leader 600-700 nucleotides long, has a long open reading frame encoding 807 amino acids and an untranslated 3'-sequence of 239 nucleotides. Four introns with a combined length of 654 bases are removed from the primary transcript. Radiosequencing of in vitro translation products shows that translation of the long open reading frame begins at the first AUG, even though it is located in an unfavourable sequence context. The transcript is found in all organs investigated, provided an active Ac is present in the stock.
各种大小的转录本与玉米中的转座因子 Ac 杂交在大多数玉米品系中。然而，在携带活性 Ac 的那些品系中发现了一种丰度为 1-3 x 10 的多聚（A）RNA 的 3.5kb mRNA。含有两个 Ac 元件的植物比含有一个 Ac 元件的植物含有略多的 3.5kb Ac 转录本。已经分离并测序了跨越大多数消息的重叠 cDNA 克隆。通过 Northern 杂交和 S1 作图确定了转录本的 5'-末端。它从几个起始位点开始，距离近 100 个碱基，包含一个无 AUG 的 600-700 个核苷酸长的前导序列，具有长的开放阅读框，编码 807 个氨基酸和 239 个核苷酸未翻译的 3'-序列。从初级转录本中去除了四个长度为 654 个碱基的内含子。体外翻译产物的放射测序表明，即使长开放阅读框的翻译起始于第一个 AUG，它位于不利的序列环境中。只要品系中存在活性 Ac，就可以在所有研究的器官中发现该转录本。
