Robinson R R, Germain R N, McKean D J, Mescher M, Seidman J G
J Immunol. 1983 Oct;131(4):2025-31.
A segment of the murine immune response-associated (Ia) antigen A beta chain mRNA has been cloned, and this cDNA clone has been used to examine the organization of the genes encoding these highly polymorphic cell surface proteins. To isolate this clone, pIA beta-1, we screened 5000 cDNA clones by a filter hybridization-selection assay using a rabbit heteroantiserum to identify the A beta chain produced in in vitro translation reactions. This clone corresponds to a segment of the mRNA encoding the beta chain of the murine I-A antigen. The 464 bp nucleotide sequence of the insert is consistent with a cDNA clone encoding the carboxyl end of the murine A beta chain. Comparison of this nucleotide sequence to a human Ia beta chain-derived cDNA clone suggests that the two clones could encode proteins that are about 90% homologous in this region. Southern blot analysis using pIA beta-1 as a probe to investigate the structure of the A beta chain gene in inbred strains of mice allows two conclusions. First, there is only one A beta chain gene homologous to this cDNA clone in each haploid mouse genome. Second, the restriction fragments encoding this gene are highly polymorphic. We postulate that the mechanism which generates polymorphic variation of the A beta chain may be involved in generating the restriction site polymorphism within or near the A beta chain gene.
一段小鼠免疫反应相关（Ia）抗原Aβ链mRNA已被克隆，并且这个cDNA克隆已被用于研究编码这些高度多态性细胞表面蛋白的基因的组织情况。为了分离这个克隆pIAβ-1，我们使用兔异种抗血清通过滤膜杂交选择试验筛选了5000个cDNA克隆，以鉴定体外翻译反应中产生的Aβ链。这个克隆对应于编码小鼠I-A抗原β链的mRNA的一个片段。插入片段的464bp核苷酸序列与编码小鼠Aβ链羧基末端的cDNA克隆一致。将这个核苷酸序列与一个源自人Iaβ链的cDNA克隆进行比较表明，这两个克隆在该区域可能编码约90%同源的蛋白质。使用pIAβ-1作为探针进行Southern印迹分析，以研究近交系小鼠中Aβ链基因的结构，得出两个结论。第一，在每个单倍体小鼠基因组中只有一个与这个cDNA克隆同源的Aβ链基因。第二，编码这个基因的限制性片段高度多态。我们推测，产生Aβ链多态性变异的机制可能参与了Aβ链基因内部或附近限制性位点多态性的产生。
