Nakayama S, Moncrief N D, Kretsinger R H
Department of Biology, University of Virginia, Charlottesville 22901.
J Mol Evol. 1992 May;34(5):416-48. doi: 10.1007/BF00162998.
In the first report in this series we described the relationships and evolution of 152 individual proteins of the EF-hand subfamilies. Here we add 66 additional proteins and define eight (CDC, TPNV, CLNB, LPS, DGK, 1F8, VIS, TCBP) new subfamilies and seven (CAL, SQUD, CDPK, EFH5, TPP, LAV, CRGP) new unique proteins, which we assume represent new subfamilies. The main focus of this study is the classification of individual EF-hand domains. Five subfamilies--calmodulin, troponin C, essential light chain, regulatory light chain, CDC31/caltractin--and three uniques--call, squidulin, and calcium-dependent protein kinase--are congruent in that all evolved from a common four-domain precursor. In contrast calpain and sarcoplasmic calcium-binding protein (SARC) each evolved from its own one-domain precursor. The remaining 19 subfamilies and uniques appear to have evolved by translocation and splicing of genes encoding the EF-hand domains that were precursors to the congruent eight and to calpain and to SARC. The rates of evolution of the EF-hand domains are slower following formation of the subfamilies and establishment of their functions. Subfamilies are not readily classified by patterns of calcium coordination, interdomain linker stability, and glycine and proline distribution. There are many homoplasies indicating that similar variants of the EF-hand evolved by independent pathways.
在本系列的第一篇报告中，我们描述了EF-手型亚家族中152种单个蛋白质的关系和进化。在此，我们又增加了66种蛋白质，并定义了八个新亚家族（CDC、TPNV、CLNB、LPS、DGK、1F8、VIS、TCBP）和七种新的独特蛋白质（CAL、SQUD、CDPK、EFH5、TPP、LAV、CRGP），我们认为它们代表了新的亚家族。本研究的主要重点是对单个EF-手型结构域进行分类。五个亚家族——钙调蛋白、肌钙蛋白C、必需轻链、调节轻链、CDC31/钙牵蛋白——以及三个独特蛋白质——钙结合蛋白、鱿鱼钙结合蛋白和钙依赖性蛋白激酶——是一致的，因为它们都从一个共同的四结构域前体进化而来。相比之下，钙蛋白酶和肌浆钙结合蛋白（SARC）各自从其自身的单结构域前体进化而来。其余19个亚家族和独特蛋白质似乎是通过对编码EF-手型结构域的基因进行易位和剪接而进化的，这些基因是上述一致的八个亚家族以及钙蛋白酶和SARC的前体。在亚家族形成及其功能确立之后，EF-手型结构域的进化速率较慢。亚家族不容易通过钙配位模式、结构域间连接子稳定性以及甘氨酸和脯氨酸分布模式进行分类。存在许多同塑性现象，表明EF-手型的相似变体是通过独立途径进化而来的。
