Middha Sumit, Wang Xinguo
Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN 47405, USA.
BMC Genomics. 2008 May 30;9:260. doi: 10.1186/1471-2164-9-260.
The fibrinogen-like (FBG) domain consists of approximately 200 amino acid residues, which has high sequence similarity to the C-terminal halves of fibrinogen beta and gamma chains. Fibrinogen-related proteins (FREPs) containing one or more FBG domains are found universally in vertebrates and invertebrates. In invertebrates, FREPs are involved in immune responses and other aspects of physiology. To understand the complexity of this gene family in Drosophila, we analyzed FREPs in twelve Drosophila species.
Using the genome data from 12 Drosophila species, we identified FBG domains in each species. The results show that the gene numbers in each species vary from 14 genes up to 43 genes. Using sequence profile analysis, we found that FBG domains have high sequence similarity and are highly conserved throughout. By comparison of structure and sequence conservation, some of the FBG domains in Drosophila melanogaster are predicted to function in recognition of carbohydrates and their derivatives on the surface of microorganisms in innate immunity.
Sequence and structural analyses show that FREP family across 12 Drosophila species contains conserved FBG domains. Expansion of the FREP families in Drosophila is mainly accounted by a major expansion of FBG domains.
纤维蛋白原样（FBG）结构域由大约200个氨基酸残基组成，与纤维蛋白原β链和γ链的C端半段具有高度的序列相似性。含有一个或多个FBG结构域的纤维蛋白原相关蛋白（FREPs）在脊椎动物和无脊椎动物中普遍存在。在无脊椎动物中，FREPs参与免疫反应和生理学的其他方面。为了了解果蝇中这个基因家族的复杂性，我们分析了12种果蝇中的FREPs。
利用12种果蝇的基因组数据，我们在每个物种中鉴定出了FBG结构域。结果表明，每个物种中的基因数量从14个到43个不等。通过序列谱分析，我们发现FBG结构域具有高度的序列相似性，并且在整个过程中高度保守。通过比较结构和序列保守性，预测黑腹果蝇中的一些FBG结构域在先天免疫中识别微生物表面的碳水化合物及其衍生物时发挥作用。
序列和结构分析表明，12种果蝇中的FREP家族包含保守的FBG结构域。果蝇中FREP家族的扩展主要是由FBG结构域的大量扩展所致。
