Berbers G A, Hoekman W A, Bloemendal H, de Jong W W, Kleinschmidt T, Braunitzer G
Eur J Biochem. 1984 Mar 15;139(3):467-79. doi: 10.1111/j.1432-1033.1984.tb08029.x.
Partial amino acid sequences of six major subunits of bovine beta-crystallin have been determined by automatic liquid-phase Edman degradation and the dansyl-Edman procedure, complemented by amino acid analyses of peptides. The results show that, including the previously established beta Bp sequence [H. P. C. Driessen et al. (1981) Eur. J. Biochem. 121, 83-91], there exist at least seven primary gene products in bovine beta-crystallin, which exhibit 40% or more sequence homology. Two of the gene products are completely identical except for the presence in one of them of 17 additional residues at the N terminus, possibly caused by differential splicing of the same primary RNA transcript. The rate of evolutionary change of the beta chains (4% sequence change per 100 X 10(6) years) is about equally slow as that of alpha-crystallin, and the gene duplications giving rise to the different chains must have occurred very early in vertebrate evolution. The beta chains can be divided into two groups, according to sequence homology and presence of deletions/insertions and C-terminal extension, on which basis a new, rational nomenclature for the beta subunits is introduced. The N-terminal extensions of all beta chains are very different in length and sequence, even between homologous beta chains in different species. Possible explanations for this finding are discussed.
通过自动液相埃德曼降解法和丹磺酰 - 埃德曼法，并辅以肽段的氨基酸分析，已确定了牛β - 晶状体蛋白六个主要亚基的部分氨基酸序列。结果表明，包括先前确定的βBp序列[H. P. C. 德里森等人（1981年），《欧洲生物化学杂志》121卷，83 - 91页]，牛β - 晶状体蛋白中至少存在七种主要基因产物，它们表现出40%或更高的序列同源性。其中两种基因产物除了其中一种在N端有17个额外的残基外完全相同，这可能是由同一初级RNA转录本的差异剪接引起的。β链的进化变化速率（每100×10⁶年有4%的序列变化）与α - 晶状体蛋白的进化变化速率大致相同，导致不同链产生的基因重复一定发生在脊椎动物进化的早期。根据序列同源性、缺失/插入的存在情况以及C端延伸情况，β链可分为两组，在此基础上引入了一种新的、合理的β亚基命名法。所有β链的N端延伸在长度和序列上都非常不同，即使是不同物种中的同源β链之间也是如此。本文讨论了这一发现的可能解释。
