生物
分子生物学
等位基因排除
基因
DNA
多核苷酸
免疫球蛋白基因
限制性酶
核酸热力学
限制性片段
胚胎
遗传学
核糖核酸
T细胞受体
免疫系统
T细胞
作者
Nobumichi Hozumi,Susumu Tonegawa
标识
DOI:10.1073/pnas.73.10.3628
摘要
A high-molecular-weight DNA from Balb/c mouse early embryo or from MOPC 321 plasmacytoma (a k-chain producer) was digested to completion with Bacillus amyloliquefaciens strain H restriction enzyme (BamH I). The resulting DNA fragments were fractionated according to size in preparative agarose gel electrophoresis. DNA fragments carrying gene sequences coding for the variable or constant region of k chains were detected by hybridization with purified, 125I-labeled, whole MOPC 321 K MRNA and with its 3'-end half. The pattern of hybridization was completely different in the genomes of embryo cells and of the plasmacytoma. The pattern of embryo DNA showed two components, one of which (molecular weight=6.0 million) hybridized with C-gene sequences and the other (molecular weight=3.9 million) with V-gene sequences. The pattern of the tumor DNA showed a single component that hybridized with both V-gene and C-gene sequences and that is smaller (molecular weight=2.4 million) than either of the components in embryo DNA. The results were interpreted to mean that the Vk and Ck genes, which are some distance away from each other in the embryo cells, are joined to form a contiguous polynucleotide stretch during differentiation of lymphocytes. Such joining occurs in both of the homologous chromosomes. Relevance of these findings with respect to models for V-C gene joining, activation of a specific V k gene, and allelic exclusion in immunoglobulin gene loci is discussed.
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