Chu M L, de Wet W, Bernard M, Ding J F, Morabito M, Myers J, Williams C, Ramirez F
Nature. 1984;310(5975):337-40. doi: 10.1038/310337a0.
The collagens represent an interesting example of a structurally related but genetically distinct family of proteins. Type I, the most abundant of the vertebrate collagens, comprises two pro alpha 1(I) chains and one pro alpha 2(I) chain, each containing terminal propeptides and a central domain of 338 (Gly, X, Y) repeats. The structure of the chicken pro alpha 2(I) gene shows an intriguing relationship between exon organization and the arrangement of (Gly, X, Y) repeats (see ref. 2 for review). This has led to the suggestion that the collagens evolved from a common ancestral unit of 54 base pairs (bp). Here we present the structure of the entire human pro alpha 1(I) gene and compare this with the chicken pro alpha 2(I). The exon arrangement of the two genes is remarkably similar, although the human pro alpha 1(I) is more compact because of the shorter length of its introns. The data strongly support the notion that the type I genes have evolved from an ancestral multi-exon unit, and that once the gene was translated, a strong evolutionary pressure caused it to maintain this elaborate structure.
胶原蛋白是一类结构相关但基因不同的蛋白质家族中的有趣例子。I型胶原蛋白是脊椎动物中最丰富的胶原蛋白，由两条α1（I）前体链和一条α2（I）前体链组成，每条链都包含末端前肽和一个由338个（甘氨酸、X、Y）重复序列组成的中央结构域。鸡α2（I）前体基因的结构显示了外显子组织与（甘氨酸、X、Y）重复序列排列之间的有趣关系（综述见参考文献2）。这导致了一种观点，即胶原蛋白是从一个54个碱基对（bp）的共同祖先单位进化而来的。在这里，我们展示了整个人类α1（I）前体基因的结构，并将其与鸡α2（I）前体基因进行比较。尽管人类α1（I）前体基因由于内含子较短而更加紧凑，但这两个基因的外显子排列非常相似。这些数据有力地支持了I型基因是从一个祖先多外显子单位进化而来的观点，并且一旦该基因被翻译，强大的进化压力使其维持这种精细的结构。
