Fukasawa K M, Li W H, Yagi K, Luo C C, Li S S
Laboratory of Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Mol Biol Evol. 1986 Jul;3(4):330-42. doi: 10.1093/oxfordjournals.molbev.a040402.
A mouse genomic clone containing a lactate dehydrogenase-A (LDH-A) processed pseudogene and a B1 repetitive element was isolated, and a nucleotide sequence of approximately 3 kb was determined. The pseudogene and B1 element are flanked by perfect 13-bp repeats, and the B1 sequence starts at 14 nucleotides 3' to the presumptive polyadenylation signal of the pseudogene. The nucleotide sequences of the LDH-A genes and processed pseudogenes from mouse, rat, and human were compared, and a phylogenetic tree was constructed. The rate and pattern of nucleotide substitutions in the LDH-A pseudogenes are similar to previously reported results (Li et al. 1984). The average rate of nucleotide substitutions in the LDH-A pseudogenes is 4.3 X 10(-9)/site/year. The substitutions of C----T and G----A are most frequent, and A----G substitutions are relatively high. The rate of synonymous substitutions in the LDH-A genes is 5.3 X 10(-9), which is not significantly higher than the average rate of 4.7 X 10(-9) for 35 mammalian genes. The rate of nonsynonymous substitutions in the LDH-A genes is 0.20 X 10(-9), which is considerably lower than the average rate of 0.88 X 10(-9) for 35 mammalian genes. Thus, the mammalian LDH-A gene appears to be highly conserved in evolution.
分离出一个包含乳酸脱氢酶 - A（LDH - A）加工假基因和一个B1重复元件的小鼠基因组克隆，并测定了约3 kb的核苷酸序列。该假基因和B1元件两侧是完美的13 bp重复序列，B1序列起始于假基因推定聚腺苷酸化信号下游14个核苷酸处。比较了小鼠、大鼠和人类的LDH - A基因及加工假基因的核苷酸序列，并构建了系统发育树。LDH - A假基因中核苷酸替换的速率和模式与先前报道的结果相似（Li等人，1984年）。LDH - A假基因中核苷酸替换的平均速率为4.3×10⁻⁹/位点/年。C→T和G→A的替换最为频繁，A→G替换相对较高。LDH - A基因中同义替换的速率为5.3×10⁻⁹，并不显著高于35个哺乳动物基因的平均速率4.7×10⁻⁹。LDH - A基因中非同义替换的速率为0.20×10⁻⁹，远低于35个哺乳动物基因的平均速率0.88×10⁻⁹。因此，哺乳动物的LDH - A基因在进化过程中似乎高度保守。
