THE COMPLEX SET OF LATE TRANSCRIPTS FROM THE DROSOPHILA SEX DETERMINATION GENE SEX-LETHAL ENCODES MULTIPLE RELATED POLYPEPTIDES
THE COMPLEX SET OF LATE TRANSCRIPTS FROM THE DROSOPHILA SEX DETERMINATION GENE SEX-LETHAL ENCODES MULTIPLE RELATED POLYPEPTIDES
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DOI：
10.1128/mcb.11.7.3584
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发表时间：
1991-07-01
影响因子：
5.3
通讯作者：
CLINE, TW
中科院分区：
文献类型：
--
作者：
SAMUELS, ME;SCHEDL, P;CLINE, TW
Sex-lethal（Sxl）是果蝇性别决定的关键基因，在果蝇胚胎发育早期表达一组3个早期转录本，在中胚发育至成年期表达一组7个晚期转录本。在晚期转录本中，男性特异性mRNA与其女性对应物的区别在于存在一个额外的外显子，该外显子中断了一个长的开放阅读框（ORF）。我们现在已经通过cDNA测序、北方（RNA）印迹、引物延伸和RNA酶保护分析了晚期Sxl转录物的结构。晚期转录物似乎使用共同的5'末端，但在其3'末端通过使用替代的多聚腺苷酸化位点而不同。其中两个位点缺乏典型的AATAAA序列，它们的使用与女性中存在功能性生殖系相关，这表明可能存在组织特异性聚腺苷酸化。除了存在男性特异性外显子外，未检测到其他性别特异性剪接事件，但观察到一些非性别特异性剪接变体。在女性中，各种形式的晚期Sxl转录物可能编码多达六种略微不同的多肽。所有的蛋白质编码差异发生在先前定义的核糖核蛋白基序之外。一类Sxl mRNA还包括与第一ORF在同一框中但通过单个赭石密码子与其分开的第二长ORF。第二个ORF的功能尚不清楚。观察到显著量的明显部分加工的Sxl RNA，这与受调节的Sxl剪接相对缓慢地发生的假设一致。
Sex-lethal (Sxl), a key sex determination gene in Drosophila melanogaster, is known to express a set of three early transcripts arising during early embryogenesis and a set of seven late transcripts occurring from midembryogenesis through adulthood. Among the late transcripts, male-specific mRNAs were distinguished from their female counterparts by the presence of an extra exon interrupting an otherwise long open reading frame (ORF). We have now analyzed the structures of the late Sxl transcripts by cDNA sequencing, Northern (RNA) blotting, primer extension, and RNase protection. The late transcripts appear to use a common 5' end but differ at their 3' ends by the use of alternative polyadenylation sites. Two of these sites lack canonical AATAAA sequences, and their use correlates in females with the presence of a functional germ line, suggesting possible tissue-specific polyadenylation. Besides the presence of the male-specific exon, no additional sex-specific splicing events were detected, although a number of non-sex-specific splicing variants were observed. In females, the various forms of late Sxl transcript potentially encode up to six slightly different polypeptides. All of the protein-coding differences occur outside the previously defined ribonucleoprotein motifs. One class of Sxl mRNAs also includes a second long ORF in the same frame as the first ORF but separated from it by a single ochre codon. The function of this second ORF is unknown. Significant amounts of apparently partially processed Sxl RNAs were observed, consistent with the hypothesis that the regulated Sxl splices occur relatively slowly.