Comparative structural analysis of the transcriptionally active proopiomelanocortin genes A and B of Xenopus laevis.
Comparative structural analysis of the transcriptionally active proopiomelanocortin genes A and B of Xenopus laevis.
复制标题
非洲爪蟾转录活性原阿黑皮素基因 A 和 B 的比较结构分析。
DOI：
10.1093/oxfordjournals.molbev.a040736
复制
发表时间：
1992
影响因子：
10.7
通讯作者：
Martens,GJ
中科院分区：
文献类型：
--
作者：
Deen,PM;Bussemakers,MJ;Terwel,D;Roubos,EW;Martens,GJ
在脑下垂体的中叶，激素原阿黑皮质素原 (POMC) 被加工成除其他肽之外的黑素细胞刺激激素 (α-MSH)。在蟾蜍中，α-MSH 在背景适应过程中控制皮肤变黑，中间叶中 POMC 基因转录的水平取决于背景的颜色。在肺叶中，两种结构不同的 POMC 蛋白由两个 mRNA 产生，这两个 mRNA 从两个 POMC 基因（A 和 B）转录到大致相同的水平。我们之前报道了非洲爪蟾 POMC 基因 B 的完整核苷酸序列。为了鉴定非洲爪蟾 POMC 基因中的保守 DNA 元件以及潜在的调控 DNA 元件，我们在此报告了非洲爪蟾 POMC 基因 A 及其 5' 和 3' 侧翼区域的完整核苷酸序列的测定和分析。两个非洲爪蟾 POMC 基因的比较显示，除了外显子之外，还发现了三个高度保守的区域。首先，启动子区域的一致性大于 90%。第二个区域涉及位于两个基因中大致相同位置的 JH12 重复元件。这些元素的相同性超过 86%。第三个区域是外显子三上游的 500 bp 序列（63% 同一性）。除了这三个大区域外，在两个 POMC 基因的相似位置还发现了几个具有显着同一性的小区域。事实上，除了 JH12 元件之外，两个 POMC 基因之间的重复元件并不保守，这表明这些重复在功能上并不重要。
In the intermediate lobe of the pituitary gland, the prohormone proopiomelanocortin (POMC) is processed to, among other peptides, melanocyte-stimulating hormone (alpha-MSH). In the toad Xenopus laevis alpha-MSH controls skin darkening during background adaptation, and the level of POMC gene transcription in the intermediate lobe depends on the color of the background. In the lobe, two structurally different POMC proteins are produced from two mRNAs that are transcribed to approximately the same level from two POMC genes (A and B). We previously reported the entire nucleotide sequence of Xenopus POMC gene B. To identify conserved-- and thus potential regulatory--DNA elements in the Xenopus POMC gene, we here report the determination and analysis of the complete nucleotide sequence of Xenopus POMC gene A and its 5'- and 3'-flanking regions. Comparison of the two Xenopus POMC genes revealed, in addition to the exons, three highly conserved regions. First, the promoter regions are greater than 90% identical. The second region concerns JH12 repetitive elements situated at approximately the same position in both genes. These elements are greater than 86% identical. The third region is a 500-bp sequence just upstream of exon three (63% identity). Besides these three large regions, several small regions with significant identity were found at similar positions in the two POMC genes. The fact that, except for the JH12 element, the repetitive elements are not conserved between the two POMC genes indicates that these repeats are not functionally important.