Brown A J, Leibold E A, Munro H N
Proc Natl Acad Sci U S A. 1983 Mar;80(5):1265-9. doi: 10.1073/pnas.80.5.1265.
The shell of the iron-storage protein ferritin consists of two types of subunit (heavy, Mr = 21,000; light, Mr = 19,000). To study the structure and expression of the ferritin subunit genes, recombinant plasmids containing ferritin cDNA have been isolated. A cDNA library was constructed in the vector pBR322 from rat liver polysomal mRNA and screened by using I125-labeled antibody to rat liver ferritin. Six positive clones were identified and were shown to contain cDNA inserts ranging in length from 800 to 950 base pairs. When these cDNA clones were used for hybrid selection of rat liver mRNA and the selected mRNAs were translated in vitro, the products from each clone migrated on denaturing gels in a position similar to that of the light subunit of ferritin. No evidence of translation of the heavy subunit was obtained, indicating that the two subunits are encoded by separate mRNAs. RNA blot analysis gave a length of 1,100 nucleotides for the light-subunit mRNA. One of the cDNA inserts was fractionated into four fragments by using the restriction enzyme Sau3A. When the fragments were hybridized with Southern blots of rat spleen DNA, each fragment yielded similar patterns of hybridization to that obtained with the intact cDNA. Therefore, all regions of the cDNA sequence contain homologous sequences to similar genomic restriction fragments. This is consistent with the existence of a family of genes that encode the light subunit of rat ferritin.
铁储存蛋白铁蛋白的外壳由两种亚基组成（重链，Mr = 21,000；轻链，Mr = 19,000）。为了研究铁蛋白亚基基因的结构和表达，已分离出含有铁蛋白cDNA的重组质粒。用大鼠肝脏多聚核糖体mRNA构建了载体为pBR322的cDNA文库，并用125I标记的大鼠肝脏铁蛋白抗体进行筛选。鉴定出6个阳性克隆，其cDNA插入片段长度在800至950个碱基对之间。当这些cDNA克隆用于大鼠肝脏mRNA的杂交选择，且所选mRNA在体外进行翻译时，每个克隆的产物在变性凝胶上的迁移位置与铁蛋白轻链亚基相似。未获得重链亚基翻译的证据，这表明这两个亚基由不同的mRNA编码。RNA印迹分析显示轻链亚基mRNA的长度为1100个核苷酸。用限制性内切酶Sau3A将其中一个cDNA插入片段切割成四个片段。当这些片段与大鼠脾脏DNA的Southern印迹杂交时，每个片段产生的杂交模式与完整cDNA的相似。因此，cDNA序列的所有区域都含有与类似基因组限制性片段的同源序列。这与存在编码大鼠铁蛋白轻链亚基的基因家族是一致的。
