Symons D B, Clarkson C A
Agricultural and Food Research Council, Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, U.K.
Mol Immunol. 1992 Nov;29(11):1407-13. doi: 10.1016/0161-5890(92)90178-z.
Southern blotting of bovine genomic DNA and hybridization with a human Fc gamma RI cDNA probe, p135, has identified a single copy of the bovine Fc gamma RI gene. A bovine genomic lymphocyte library in lambda EMBL3 was screened with probe p135. A positive lambda clone, 15.5.4, containing the three extracellular domain exons of Fc gamma RI, has been cloned, mapped and sequenced. Each extracellular domain is encoded within a single exon. All three domains are assigned to the C-2 set of the Ig superfamily with 58% identity between amino acid residues of bovine, human and mouse Fc gamma RI. Pairs of cysteine residues are conserved in each domain as potential sites for intra-chain disulphide bonding. Human monocytoid U937 cells were used as a model to test binding homology within the Fc gamma RI family. The binding of IgG isotypes to IFN-gamma stimulated U937 cells was determined by FACScan flow cytometry. U937 cell Fc gamma RI receptor does not bind bovine or ovine IgG isotypes. On the basis of these studies and by comparison of the Fc determinant region sequences of IgG, the introduction of species specificity in Fc gamma RI/IgG interaction by evolutionary drift is proposed.
用牛基因组DNA进行Southern印迹分析，并与人FcγRI cDNA探针p135杂交，已鉴定出牛FcγRI基因的单拷贝。用探针p135筛选λEMBL3中的牛基因组淋巴细胞文库。已克隆、定位并测序了一个阳性λ克隆15.5.4，其包含FcγRI的三个细胞外结构域外显子。每个细胞外结构域由单个外显子编码。所有三个结构域都被归入Ig超家族的C-2组，牛、人和小鼠FcγRI的氨基酸残基之间具有58%的同一性。每个结构域中一对半胱氨酸残基保守，作为链内二硫键结合的潜在位点。人单核细胞样U937细胞被用作模型来测试FcγRI家族内的结合同源性。通过FACScan流式细胞术测定IgG同种型与IFN-γ刺激的U937细胞的结合。U937细胞FcγRI受体不结合牛或羊IgG同种型。基于这些研究并通过比较IgG的Fc决定簇区域序列，提出通过进化漂变在FcγRI/IgG相互作用中引入物种特异性。
