Evans M J, Scarpulla R C
Department of Molecular Biology, Northwestern University Medical School, Chicago, IL 60611.
Proc Natl Acad Sci U S A. 1988 Dec;85(24):9625-9. doi: 10.1073/pnas.85.24.9625.
We have isolated and determined the DNA sequences of the human somatic cytochrome c gene (HCS) and 11 processed pseudogenes. HCS is the functional homologue to the previously characterized rat somatic gene because it correctly encodes the human heart protein, is present in single copy in the human genome, is nearly identical in both size and intron/exon structure to rodent somatic genes, and shares a high degree of sequence homology with its rat counterpart including a well-conserved promoter region (77% over 250 nucleotides). In contrast to the rodent system, however, where the known pseudogenes all originated from a locus encoding the present day cytochrome c, the human pseudogenes are of two types. A predominant class of older pseudogenes came from a progenitor of HCS that encoded an ancestral form of the protein, while a second group of only a few young pseudogenes originated from a recent parent of HCS that encoded the current cytochrome c polypeptide. These two distinct classes of human pseudogenes provide a molecular record of the history of cytochrome c evolution in primates and demarcate a short period of rapid evolution of the functional gene.
我们已经分离并确定了人类体细胞细胞色素c基因（HCS）和11个加工假基因的DNA序列。HCS是先前鉴定的大鼠体细胞基因的功能同源物，因为它能正确编码人类心脏蛋白，在人类基因组中以单拷贝形式存在，在大小和内含子/外显子结构上与啮齿动物体细胞基因几乎相同，并且与其大鼠对应物具有高度的序列同源性，包括一个保守性良好的启动子区域（在250个核苷酸上有77%的同源性）。然而，与啮齿动物系统不同，在啮齿动物系统中，已知的假基因都起源于一个编码当今细胞色素c的基因座，而人类假基因有两种类型。一类主要的较古老假基因来自HCS的一个祖先基因，该祖先基因编码该蛋白质的一种原始形式，而另一组只有少数年轻假基因起源于HCS的一个近期亲本基因，该亲本基因编码当前的细胞色素c多肽。这两类不同的人类假基因提供了灵长类动物细胞色素c进化历史的分子记录，并划定了功能基因快速进化的一个短暂时期。
