EVOLUTION OF THE CYTOCHROME-B GENE OF MAMMALS
EVOLUTION OF THE CYTOCHROME-B GENE OF MAMMALS
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DOI：
10.1007/bf02515385
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发表时间：
1991-02-01
影响因子：
3.9
通讯作者：
WILSON, AC
中科院分区：
文献类型：
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作者：
IRWIN, DM;KOCHER, TD;WILSON, AC
通过聚合酶链式反应(PCR)和通用的引物扩增细胞色素b基因全长(约1140bp)，我们获得了17个完整的基因序列，分别代表有蹄哺乳动物(有蹄类)和海豚(鲸目)三个目。一些有蹄类动物的化石记录可以估计细胞色素b、DNA和氨基酸序列的各种成分的进化率。密码子中第一、第二和第三位置的相对替换率为10：1到至少33。对于深度分化(>；500万年)，这种线粒体基因中的替换和沉默颠换似乎都可以用于系统发育推断。系统发育的发现包括：(1)鲸目动物、偶氮蹄目动物和近足趾动物，排除大象和人类；(2)叉角羚和休闲鹿，排除牛类(即牛、绵羊和山羊)；(3)绵羊和山羊，排除其他山核桃(即牛、长颈鹿、鹿和叉角羚)；以及(4)高级反刍动物，排除山雀和其他偶蹄目动物。对这些细胞色素b序列的比较支持目前这种跨膜蛋白的结构-功能模型。外表面包括Q(O)氧化还原中心的部分比分子的其余部分更受限制，即跨膜片段和突出到线粒体基质中的表面。跨膜片段中的许多氨基酸替换是疏水残基(特别是亮氨酸、异亮氨酸和缬氨酸)之间的交换。与其他蛋白质编码序列类似，密码子第一和第二位置的替换变化近似于负二项分布。在密码子的四重简并位置，核苷酸替换近似于泊松分布，这意味着潜在的突变谱相对于位置是随机的。
With the polymerase chain reaction (PCR) and versatile primers that amplify the whole cytochrome b gene (approximately 1140 bp), we obtained 17 complete gene sequences representing three orders of hoofed mammals (ungulates) and dolphins (cetaceans). The fossil record of some ungulate lineages allowed estimation of the evolutionary rates for various components of the cytochrome b DNA and amino acid sequences. The relative rates of substitution at first, second, and third positions within codons are in the ratio 10 to 1 to at least 33. For deep divergences (> 5 million years) it appears that both replacements and silent transversions in this mitochondrial gene can be used for phylogenetic inference. Phylogenetic findings include the association of (1) cetaceans, artiodactyls, and perissodactyls to the exclusion of elephants and humans, (2) pronghorn and fallow deer to the exclusion of bovids (i.e., cow, sheep, and goat), (3) sheep and goat to the exclusion of other pecorans (i.e., cow, giraffe, deer, and pronghorn), and (4) advanced ruminants to the exclusion of the chevrotain and other artiodactyls. Comparisons of these cytochrome b sequences support current structure-function models for this membrane-spanning protein. That part of the outer surface which includes the Q(o) redox center is more constrained than the remainder of the molecule, namely, the transmembrane segments and the surface that protrudes into the mitochondrial matrix. Many of the amino acid replacements within the transmembrane segments are exchanges between hydrophobic residues (especially leucine, isoleucine, and valine). Replacement changes at first and second positions of codons approximate a negative binomial distribution, similar to other protein-coding sequences. At four-fold degenerate positions of codons, the nucleotide substitutions approximate a Poisson distribution, implying that the underlying mutational spectrum is random with respect to position.