Wang Y Z, Patterson J, Gray J E, Yu C, Cottrell B A, Shimizu A, Graham D, Riley M, Doolittle R F
Center for Molecular Genetics, University of California, San Diego, La Jolla 92093.
Biochemistry. 1989 Dec 12;28(25):9801-6. doi: 10.1021/bi00451a039.
The complete amino acid sequence of the lamprey fibrinogen alpha chain has been determined by a combination of peptide sequencing and cDNA and genomic cloning. The chain, which has an apparent molecular weight by dodecyl sulfate-polyacrylamide gel electrophoresis of ca. 100,000, is composed of 961 amino acid residues and has a calculated molecular weight of 96,722. It is distinguished by a large number of 18-residue repeats in a region where mammalian fibrinogens have 13-residue repeats. The data are in accord with our previous finding that the lamprey alpha chain has a distinctive amino acid composition, almost half the residues being glycine, serine, or threonine. The chain differs from mammalian alpha chains in that there are no cysteines in the carboxy-terminal half, and thus no intrachain loop, nor are there any RGD sequences in the lamprey alpha chain. Taken together with previous data on the sequences of the beta and gamma chains, the findings bear significantly on our understanding of fibrin formation. The alpha chain also provides an interesting case of structural convergence during evolution.
通过肽测序与cDNA及基因组克隆相结合的方法，已确定了七鳃鳗纤维蛋白原α链的完整氨基酸序列。该链经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定的表观分子量约为100,000，由961个氨基酸残基组成，计算分子量为96,722。其特点是在哺乳动物纤维蛋白原有13个残基重复的区域存在大量18个残基的重复序列。这些数据与我们之前的发现一致，即七鳃鳗α链具有独特的氨基酸组成，几乎一半的残基为甘氨酸、丝氨酸或苏氨酸。该链与哺乳动物α链的不同之处在于，其羧基末端的一半没有半胱氨酸，因此没有链内环，七鳃鳗α链中也没有任何RGD序列。结合之前关于β链和γ链序列的数据，这些发现对我们理解纤维蛋白的形成具有重要意义。α链在进化过程中还提供了一个有趣的结构趋同案例。
