Dixon B, Stet R J, van Erp S H, Pohajdak B
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Immunogenetics. 1993;38(1):27-34. doi: 10.1007/BF00216387.
Using degenerate primers based on published beta 2-microglobulin sequences we were able to obtain an expected 111 base pairs (bp) polymerase chain reaction (PCR) fragment from tilapia genomic DNA. The sequence of this fragment showed a high degree of similarity to mouse beta 2-microglobulin at the protein level. We used these primers in an "anchored PCR" to obtain a 213 bp PCR fragment from a carp cDNA library. This was then used to clone a full-length beta 2-microglobulin cDNA from carp. The carp sequence showed the highest similarity to rabbit beta 2-microglobulin. Both sequences showed strong similarities to all previously published vertebrate beta 2-microglobulin sequences. The predicted protein secondary structure of both the carp and tilapia clones was almost identical to the corresponding regions of previously known vertebrate beta 2-microglobulin protein sequences. When either the carp or tilapia probes were used against corresponding northern blots, they hybridized to a message of approximately 800-1000 bases long, which corresponds to the previously published lengths of beta 2-microglobulin mRNAs. Southern blotting indicated that beta 2-microglobulin was encoded by a single copy gene in both cases. Phylogenetic analysis indicated that the sequences were related to the beta 2-microglobulins of higher vertebrates but grouped together in an ancestral position.
基于已发表的β2-微球蛋白序列设计简并引物，我们从罗非鱼基因组DNA中成功获得了预期的111个碱基对（bp）的聚合酶链反应（PCR）片段。该片段的序列在蛋白质水平上与小鼠β2-微球蛋白具有高度相似性。我们将这些引物用于“锚定PCR”，从鲤鱼cDNA文库中获得了一个213 bp的PCR片段。随后利用该片段从鲤鱼中克隆出全长β2-微球蛋白cDNA。鲤鱼序列与兔β2-微球蛋白的相似性最高。这两个序列与所有先前发表的脊椎动物β2-微球蛋白序列都有很强的相似性。鲤鱼和罗非鱼克隆体的预测蛋白质二级结构与先前已知的脊椎动物β2-微球蛋白蛋白质序列的相应区域几乎相同。当用鲤鱼或罗非鱼探针与相应的Northern杂交膜杂交时，它们与一条长度约为800 - 1000个碱基的信息杂交，这与先前发表的β2-微球蛋白mRNA长度相对应。Southern印迹分析表明，在这两种情况下β2-微球蛋白均由单拷贝基因编码。系统发育分析表明，这些序列与高等脊椎动物的β2-微球蛋白相关，但在一个祖先位置上聚在一起。
