Varshney U, Hoar D I, Starozik D, Gedamu L
Mol Biol Med. 1984 Jun;2(3):193-206.
Genomic blot analysis of human DNA indicated that metallothioneins are represented by a multi-gene family. Clones containing metallothionein sequences have been isolated and two of these have been identified as metallothionein-I and metallothionein-II processed genes by sequence analysis. The metallothionein-II processed gene in humans shows two restriction fragment length polymorphisms of 4.5 and 4.8 kb (10(3) bases) when EcoRI-digested genomic DNA from various individuals was analysed by Southern blotting. All the three genotypes are found at a high frequency and thus the metallothionein-II processed gene represents a true polymorphic marker. Familial studies also indicate that these restriction fragment length polymorphisms follow the classical Mendelian inheritance. Detailed Southern blot analyses show that this restriction fragment length polymorphism is due to a restriction site polymorphism and is localized at the 5'-flanking region of the metallothionein-II processed gene. Sequence analysis of the suspected region in the 4.8 kb fragment shows that the sequence G*GATTC, which is found 371 nucleotides downstream from the EcoRI site on the 5' end of the 4.8 kb fragment, makes a HinfI site. A transition of *G to A in this sequence in the 4.5 kb allele has resulted in loss of the HinfI site and created an EcoRI site. Thus, this mutation has given rise to this restriction fragment length polymorphism.
对人类DNA进行的基因组印迹分析表明，金属硫蛋白由一个多基因家族代表。含有金属硫蛋白序列的克隆已被分离出来，其中两个通过序列分析被鉴定为金属硫蛋白-I和金属硫蛋白-II加工基因。当通过Southern印迹分析来自不同个体的经EcoRI消化的基因组DNA时，人类中的金属硫蛋白-II加工基因显示出4.5和4.8 kb（10³个碱基）的两种限制性片段长度多态性。所有这三种基因型都以高频率出现，因此金属硫蛋白-II加工基因代表一个真正的多态性标记。家族研究还表明，这些限制性片段长度多态性遵循经典的孟德尔遗传。详细的Southern印迹分析表明，这种限制性片段长度多态性是由于一个限制性位点多态性，并且定位在金属硫蛋白-II加工基因的5'侧翼区域。对4.8 kb片段中可疑区域的序列分析表明，在4.8 kb片段5'端的EcoRI位点下游371个核苷酸处发现的序列GGATTC形成了一个HinfI位点。在4.5 kb等位基因的该序列中G到A的转变导致了HinfI位点的丢失并产生了一个EcoRI位点。因此，这种突变产生了这种限制性片段长度多态性。
