Unexpected beta2-microglobulin sequence diversity in individual rainbow trout.
Unexpected beta2-microglobulin sequence diversity in individual rainbow trout.
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虹鳟鱼个体中意外的 β2-微球蛋白序列多样性。
DOI：
10.1073/pnas.93.7.2779
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发表时间：
1996
影响因子：
11.1
通讯作者：
Parham,P
中科院分区：
文献类型：
--
作者：
Shum,BP;Azumi,K;Zhang,S;Kehrer,SR;Raison,RL;Detrich,HW;Parham,P
对于哺乳动物来说，主要组织相容性复合体(MHC)I类分子的轻链Beta2-微球蛋白(Beta2m)是不变的(或高度保守的)，由与MHC无关的单个基因编码。我们发现，一种鲑科鱼类--虹鲑鱼(Oncorhynchus MykISS)的β2m并不符合哺乳动物的范式。在随机选择的12个个体鱼的Beta2m cDNA克隆中，有10个具有不同的核苷酸序列。在虹鲑鱼中观察到了一个复杂的限制性片段长度多态模式，这表明基因组中有多个Beta2m基因，超过了祖先鲑鱼四倍体的两个基因。随后可能发生了Beta2m基因的额外复制和多样化。β2m基因序列的变异主要发生在不干扰成熟的Beta2m蛋白结构的位置，表明所观察到的鲑鱼Beta2m基因的多样性主要不是病原体选择的结果。
For mammals beta2-microglobulin (beta2m), the light chain of major histocompatibility complex (MHC) class I molecules, is invariant (or highly conserved) and is encoded by a single gene unlinked to the MHC. We find that beta2m of a salmonid fish, the rainbow trout (Oncorhynchus mykiss), does not conform to the mammalian paradigm. Ten of 12 randomly selected beta2m cDNA clones from an individual fish have different nucleotide sequences. A complex restriction fragment length polymorphism pattern is observed with rainbow trout, suggesting multiple beta2m genes in the genome, in excess of the two genes expected from the ancestral salmonid tetraploidy. Additional duplication and diversification of the beta2m genes might have occurred subsequently. Variation in the beta2m cDNA sequences is mainly at sites that do not perturb the structure of the mature beta2m protein, showing that the observed diversity of the trout beta2m genes is not primarily a result of pathogen selection.