Ohta T
National Institute of Genetics, Mishima, Japan.
Genetics. 1993 Aug;134(4):1271-6. doi: 10.1093/genetics/134.4.1271.
The growth hormone-prolactin gene family in mammals is an interesting example of evolution by gene duplication. Divergence among members of duplicated gene families and among species was examined by using reported gene sequences of growth hormone, prolactin and their receptors. Sequence divergence among species was found to show a general tendency in which a generation-time effect is pronounced for synonymous substitutions but not so for nonsynonymous substitutions. Divergence among duplicated genes is characterized by the relatively high rate of nonsynonymous substitutions, i.e., the rate is close to that of synonymous ones. In view of the stage- and tissue-specific expression of duplicated genes, some of the amino acid substitutions among duplicated genes is likely to be caused by positive Darwinian selection.
哺乳动物中的生长激素 - 催乳素基因家族是基因复制进化的一个有趣例子。通过使用已报道的生长激素、催乳素及其受体的基因序列,研究了复制基因家族成员之间以及物种之间的差异。发现物种间的序列差异呈现出一种普遍趋势,即同义替换的世代时间效应明显,而异义替换则不然。复制基因之间的差异表现为相对较高的非同义替换率,即该速率接近同义替换率。鉴于复制基因的阶段和组织特异性表达,复制基因之间的一些氨基酸替换可能是由正向达尔文选择引起的。