Oceanographic Center of Vigo, Spanish Institute of Oceanography-IEO, Subida a Radio Faro 50, 36390 Vigo, Pontevedra, Spain.
Immunogenetics. 2013 Jul;65(7):531-41. doi: 10.1007/s00251-013-0692-y. Epub 2013 Apr 5.
Immunoglobulin loci of two representatives of the order Crocodylia were studied from full genome sequences. Both Alligator mississippiensis and Crocodylus porosus have 13 genes for the heavy chain constant regions of immunoglobulins. The IGHC locus contains genes encoding four immunoglobulins M (IgM), one immunoglobulin D (IgD), three immunoglobulins A (IgA), three immunoglobulins Y (IgY), and two immunoglobulins D2 (IgD2). IgA and IgD2 genes were found in reverse transcriptional orientation compared to the other Ig genes. The IGHD gene contains 11 exons, four of which containing stop codons or sequence alterations. As described in other reptiles, the IgD2 is a chimeric Ig with IgA- and IgD-related domains. This work clarifies the origin of bird IgA and its evolutionary relationship with amphibian immunoglobulin X (IgX) as well as their links with mammalian IgA.
从全基因组序列研究了两种鳄形目动物的免疫球蛋白基因座。密西西比鳄和湾鳄都有 13 个重链免疫球蛋白恒定区基因。IGHC 基因座包含编码四种免疫球蛋白 M（IgM）、一种免疫球蛋白 D（IgD）、三种免疫球蛋白 A（IgA）、三种免疫球蛋白 Y（IgY）和两种免疫球蛋白 D2（IgD2）的基因。与其他 Ig 基因相比，IgA 和 IgD2 基因以反转录的方向排列。IGHD 基因包含 11 个外显子，其中四个含有终止密码子或序列改变。与其他爬行动物描述的一样，IgD2 是一种嵌合 Ig，具有 IgA 和 IgD 相关结构域。这项工作阐明了鸟类 IgA 的起源及其与两栖类免疫球蛋白 X（IgX）的进化关系，以及它们与哺乳动物 IgA 的联系。
