Schmidt C J, Jubier M F, Hamer D H
J Biol Chem. 1985 Jun 25;260(12):7731-7.
Three members of the human metallothionein-I gene family have been cloned and characterized. Two of the genes encode closely related but distinct metallothionein-I subtypes. Both of these genes are functional as shown by their transcription in cultured hepatoblastoma cells and by their ability to render transfected cells resistant to cadmium toxicity. The cotranscription of these nonallelic genes shows that the previously observed microheterogeneity of metallothionein-I protein preparations is due to the expression of distinct gene products. The third clone is incapable of encoding a typical metallothionein due to an early termination codon and two nonconservative amino acid replacements. This nonfunctional pseudogene retains introns. Evolutionary comparisons reveal conserved DNA sequences in both the coding and regulatory regions of these genes.
人类金属硫蛋白-I基因家族的三个成员已被克隆和鉴定。其中两个基因编码密切相关但不同的金属硫蛋白-I亚型。这两个基因都是有功能的，这体现在它们在培养的肝母细胞瘤细胞中的转录情况以及使转染细胞对镉毒性产生抗性的能力上。这些非等位基因的共转录表明，先前观察到的金属硫蛋白-I蛋白制剂的微异质性是由于不同基因产物的表达所致。第三个克隆由于一个早期终止密码子和两个非保守氨基酸替换而无法编码典型的金属硫蛋白。这个无功能的假基因保留了内含子。进化比较揭示了这些基因的编码区和调控区中保守的DNA序列。
