Sather S, Agabian N
Proc Natl Acad Sci U S A. 1985 Sep;82(17):5695-9. doi: 10.1073/pnas.82.17.5695.
The approximately 15 alpha- and 15 beta-tubulin genes of Trypanosoma brucei are arranged in a tandem array of alternating alpha- and beta-tubulin genes. We have examined the structure of mRNA transcripts from the tubulin gene family and have found at the 5' ends of both alpha- and beta-tubulin messages a 35-nucleotide spliced leader (SL) identical to that identified previously on the 5' ends of variant surface glycoprotein (VSG) mRNAs. No 35-nucleotide SL sequences were encoded in the tubulin intergenic regions; instead, the SL sequence apparently originates from small RNA transcripts encoded at sites that are unlinked to the tubulin genes. The tandem arrangement of the tubulin genes and the presence of the SL at the 5' end of both alpha- and beta-tubulin transcripts establishes that RNA joining between the SL and tubulin mRNA occurs in trans.
布氏锥虫约15个α-微管蛋白基因和15个β-微管蛋白基因以α-微管蛋白基因和β-微管蛋白基因交替排列的串联阵列形式存在。我们研究了微管蛋白基因家族mRNA转录本的结构，发现在α-和β-微管蛋白信息的5'端都有一个35个核苷酸的剪接前导序列（SL），与先前在变异表面糖蛋白（VSG）mRNA的5'端鉴定的序列相同。在微管蛋白基因间区域没有编码35个核苷酸的SL序列；相反，SL序列显然起源于在与微管蛋白基因不连锁的位点编码的小RNA转录本。微管蛋白基因的串联排列以及α-和β-微管蛋白转录本5'端都存在SL，这表明SL与微管蛋白mRNA之间的RNA连接是反式发生的。
