Department of Immunobiology, College of Medicine, University of Arizona, Tucson, AZ 85719, USA.
Dev Comp Immunol. 2010 Feb;34(2):189-95. doi: 10.1016/j.dci.2009.09.008. Epub 2009 Oct 7.
Beta 2 microglobulin (beta2m) is an essential subunit of major histocompatibility complex (MHC) type I molecules. In this report, beta2m cDNAs were identified and sequenced from sandbar shark spleen cDNA library. Sandbar shark beta2m gene encodes one amino acid less than most teleost beta2m genes, and 3 amino acids less than mammal beta2m genes. Although sandbar shark beta2m protein contains one beta sheet less than that of human in the predicted protein structure, the overall structure of beta2m proteins is conserved during evolution. Germline gene for the beta2m in sandbar and nurse shark is present as a single locus. It contains three exons and two introns. CpG sites are evenly distributed in the shark beta2m loci. Several DNA repeat elements were also identified in the shark beta2m loci. Sequence analysis suggests that the beta2m locus is not linked to the MHC I loci in the shark genome.
β2 微球蛋白（β2m）是主要组织相容性复合体（MHC）I 类分子的必需亚基。在本报告中，从沙虎鲨脾脏 cDNA 文库中鉴定和测序了β2m cDNA。沙虎鲨β2m 基因编码的氨基酸比大多数硬骨鱼β2m 基因少 1 个，比哺乳动物β2m 基因少 3 个。尽管沙虎鲨β2m 蛋白在预测的蛋白质结构中比人少 1 个β 片层，但在进化过程中β2m 蛋白的整体结构是保守的。沙虎鲨和护士鲨β2m 的种系基因作为单个基因座存在。它包含三个外显子和两个内含子。CpG 位点在鲨鱼β2m 基因座中均匀分布。在鲨鱼β2m 基因座中还鉴定出了几个 DNA 重复元件。序列分析表明，β2m 基因座在鲨鱼基因组中与 MHC I 基因座不连锁。
