Fayngerts Svetlana A, Najakshin Alexander M, Taranin Alexander V
Laboratory of Immunogenetics, Institute of Cytology and Genetics, Novosibirsk, Russia.
Immunogenetics. 2007 Jun;59(6):493-506. doi: 10.1007/s00251-007-0208-8. Epub 2007 Mar 14.
In primates and rodents, the extended FcR family is comprised of three subsets: classical FcRs, structurally diverse cell surface receptors currently designated FCRL1-FCRL6, and intracellular proteins FCRLA and FCRLB. Using bioinformatic analysis, we revealed the FcR-like genes of the same three subsets in the genome of dog, another representative of placental mammals, and in the genome of short-tailed opossum, a representative of marsupials. In contrast, a single FcR-like gene was found in the current version of the chicken genome. This in silico finding was confirmed by the gene cloning and subsequent Southern blot hybridization. The chicken FCRL gene encodes a cell surface receptor with the extracellular region composed of four Ig-like domains of the D1-, D2-, D3-, and D4-subtypes. The gene is expressed in lymphoid and non-lymphoid tissues. Phylogenetic analysis of the mammalian and chicken genes suggested that classical FcRs, FCRLA, and FCRLB emerged after the mammalian-avian split but before the eutherian-marsupial radiation. The data obtained show that the repertoire of the classical FcRs and surface FcR-like proteins in mammalian species was shaped by an extensive recombination process, which resulted in domain shuffling and species-specific gain and loss of distinct exons or entire genes.
在灵长类动物和啮齿动物中，扩展的FcR家族由三个亚集组成：经典FcR、目前命名为FCRL1 - FCRL6的结构多样的细胞表面受体，以及细胞内蛋白FCRLA和FCRLB。通过生物信息学分析，我们在胎盘哺乳动物的另一个代表——狗的基因组，以及有袋动物的代表——短尾负鼠的基因组中，发现了同样三个亚集的FcR样基因。相比之下，在当前版本的鸡基因组中仅发现了一个FcR样基因。这一计算机模拟结果通过基因克隆及随后的Southern印迹杂交得到了证实。鸡FCRL基因编码一种细胞表面受体，其胞外区域由D1 -、D2 -、D3 -和D4 -亚型的四个Ig样结构域组成。该基因在淋巴组织和非淋巴组织中表达。对哺乳动物和鸡基因的系统发育分析表明，经典FcR、FCRLA和FCRLB在哺乳动物与鸟类分化之后、真兽类与有袋类辐射之前出现。所获得的数据表明，哺乳动物物种中经典FcR和表面FcR样蛋白的库是由广泛的重组过程形成的，这导致了结构域重排以及不同外显子或整个基因的物种特异性增减。
