McLenachan P A, Lockhart P J, Faber H R, Mansfield B C
Department of Microbiology and Genetics, Massey University, Palmerston North, New Zealand.
J Mol Evol. 1996 Feb;42(2):273-80. doi: 10.1007/BF02198854.
The pregnancy-specific beta 1-glycoproteins (PSG) form a large family of closely related proteins. Using newly developed methods of sequence analysis, in combination with protein modeling, we provide a framework for investigating the evolution and biological function of genes like the PSG. Evolutionary trees, based on C-terminal sequence, group PSG genes in a manner consistent with their genomic organization. Trees constructed using the N-terminal domain sequences are unreliable as an indicator of phylogeny because of non-neutral processes of sequence change. During duplication of the PSG genes, evolutionary pressures have resulted in a gradient of constrained change across each gene. The N-terminal domains show a nonrandom pattern of amino acid substitutions clustered in the immunoglobulin complementarity-determining region (CDR)-like regions, which appear to be important in the function of the protein.
妊娠特异性β1-糖蛋白（PSG）构成了一个由密切相关蛋白质组成的大家族。利用新开发的序列分析方法，并结合蛋白质建模，我们为研究像PSG这样的基因的进化和生物学功能提供了一个框架。基于C端序列构建的进化树，以与其基因组组织一致的方式对PSG基因进行分组。由于序列变化的非中性过程，使用N端结构域序列构建的树作为系统发育指标并不可靠。在PSG基因复制过程中，进化压力导致每个基因的受限变化呈梯度分布。N端结构域显示出氨基酸取代的非随机模式，这些取代聚集在免疫球蛋白互补决定区（CDR）样区域，这似乎对蛋白质的功能很重要。
