Deen P M, Roubos E W, Martens G J
Department of Animal Physiology, University of Nijmegen, The Netherlands.
Mol Gen Genet. 1991 Dec;230(3):491-3. doi: 10.1007/BF00280307.
Restriction mapping of the two proopiomelanocortin (POMC) genes of the South African clawed toad Xenopus laevis revealed that POMC gene A is much larger than POMC gene B. Here we report that this size difference is mainly due to the presence of four vitellogenin (Vi)-transposon-like elements in POMC gene A, while Vi elements are absent from POMC gene B. Alignment of these elements with other Vi elements revealed a consensus sequence of 463 bp, which is bounded by a 16 bp inverted repeat and flanked by a 3 bp direct repeat. Since the amounts of mRNA produced by both POMC genes in the pars intermedia of the Xenopus pituitary are similar, the presence of the Vi-transposon-like elements in POMC gene A apparently has no effect on POMC gene expression at transcriptional or post-transcriptional levels.
对南非爪蟾非洲爪蟾的两个阿黑皮素原（POMC）基因进行限制酶切图谱分析发现，POMC基因A比POMC基因B大得多。在此我们报告，这种大小差异主要是由于POMC基因A中存在四个类卵黄蛋白原（Vi）转座子样元件，而POMC基因B中不存在Vi元件。将这些元件与其他Vi元件进行比对，发现一个463 bp的共有序列，其两侧为16 bp的反向重复序列，侧翼为3 bp的正向重复序列。由于非洲爪蟾垂体中间部的两个POMC基因产生的mRNA量相似，POMC基因A中类Vi转座子样元件的存在显然在转录或转录后水平上对POMC基因表达没有影响。
