Yang F, Luna V J, McAnelly R D, Naberhaus K H, Cupples R L, Bowman B H
Nucleic Acids Res. 1985 Nov 25;13(22):8007-17. doi: 10.1093/nar/13.22.8007.
The group-specific component (Gc) is a plasma protein that binds vitamin D. Recent characterization of human Gc cDNA demonstrated homology with serum albumin and alpha-fetoprotein. This study compares the sequences of the three proteins and demonstrates a strong evolutionary relationship. Albumin, alpha-fetoprotein and Gc evolved from an ancestral gene containing an intragenic triplication. Comparison of the amino acid sequences and patterns of double disulfide bonds suggests that the Gc gene may have diverged from an ancestral gene earlier in evolution than the genes encoding albumin and alpha-fetoprotein. Analysis of the amino acid and nucleotide sequences of the three internal domains of Gc revealed 19-23% amino acid sequence identity and the localization of three homology blocks with 40-44% nucleotide sequence identity. The deduced amino sequence of Gc furnished data for comparing its molecular configuration based on the predicted secondary structure with those predicted for human albumin and alpha-fetoprotein. Utilization of Gc cDNA has also led to the identification of its genomic DNA and detection of a human DNA polymorphism.
群体特异性成分（Gc）是一种能结合维生素D的血浆蛋白。最近对人Gc cDNA的特性分析表明，它与血清白蛋白和甲胎蛋白具有同源性。本研究比较了这三种蛋白质的序列，并证明了它们之间存在密切的进化关系。白蛋白、甲胎蛋白和Gc由一个包含基因内重复序列的祖先基因进化而来。氨基酸序列和双二硫键模式的比较表明，Gc基因在进化过程中可能比编码白蛋白和甲胎蛋白的基因更早地从祖先基因中分化出来。对Gc三个内部结构域的氨基酸和核苷酸序列分析显示，氨基酸序列同一性为19 - 23%，并且存在三个具有40 - 44%核苷酸序列同一性的同源性区域。Gc推导的氨基酸序列为基于预测二级结构比较其分子构型与人类白蛋白和甲胎蛋白的预测构型提供了数据。Gc cDNA的应用还导致了其基因组DNA的鉴定以及人类DNA多态性的检测。
