Knöchel W, Meyerhof W, Stalder J, Weber R
Nucleic Acids Res. 1985 Nov 11;13(21):7899-908. doi: 10.1093/nar/13.21.7899.
The complete nucleotide sequence of the cDNA insert of the clone pXGL25 derived from the larval beta II-globin mRNA of Xenopus laevis has been determined. The sequence of 593 nucleotides represents part of the 5'nontranslated region, the coding region for 146 amino acids and the entire 3'nontranslated region. It diverges from the related larval beta I-sequence by 24.9% in the coding region. Alignment of the 5' and 3'nontranslated regions of the two related larval beta-sequences to maximum matching resulted in 31.2% and 46.7% divergence, respectively. Divergence between the corresponding adult and larval sequences considerably exceeds that of related larval sequences, suggesting that larval genes may have arisen by gene duplication prior to genome duplication. In contrast to mammalian beta-globin mRNAs, replacement and silent base substitutions are equally abundant, thus indicating less functional constraint on the larval Xenopus laevis beta-globin chains. The larval beta I- and beta II-globins diverge by 30.8% and show most variation in the alpha 1/beta 2-chain interaction sites.
已确定从非洲爪蟾幼虫βII - 珠蛋白mRNA衍生的克隆pXGL25的cDNA插入片段的完整核苷酸序列。593个核苷酸的序列代表5'非翻译区的一部分、146个氨基酸的编码区以及整个3'非翻译区。其编码区与相关幼虫βI - 序列的差异为24.9%。将两个相关幼虫β - 序列的5'和3'非翻译区进行最大匹配比对,结果差异分别为31.2%和46.7%。相应的成体和幼虫序列之间的差异大大超过相关幼虫序列之间的差异,这表明幼虫基因可能是在基因组复制之前通过基因复制产生的。与哺乳动物β - 珠蛋白mRNA不同,置换和沉默碱基替换同样丰富,因此表明非洲爪蟾幼虫β - 珠蛋白链上的功能限制较少。幼虫βI - 和βII - 珠蛋白的差异为30.8%,并且在α1/β2 - 链相互作用位点显示出最大的变异。