Welply J K, Fowler A V, Beckwith J R, Zabin I
J Bacteriol. 1980 May;142(2):732-4. doi: 10.1128/jb.142.2.732-734.1980.
The positions of three Escherichia coli lacZ operator-proximal nonsense mutations and one deletion mutation have been determined. The nonsense mutations were suppressed with supF, resulting in the production of active beta-galactosidase by each strain. Amino acid sequencing identified the positions of the tyrosine residues inserted by supF, and thereby established that nonsense mutations lacZ2, lacZ2246, and lacZU131 are at sites corresponding to amino acids 23, 36, and 41 of beta-galactosidase, respectively. The deletion mutant, lacZM112, produced a dimeric beta-galactosidase protein missing amino acid residues 23 through 31 of the native enzyme.
已确定三种大肠杆菌乳糖操纵子近端无义突变和一种缺失突变的位置。这些无义突变被supF抑制，使得每个菌株都能产生活性β-半乳糖苷酶。氨基酸测序确定了supF插入的酪氨酸残基的位置，从而确定无义突变lacZ2、lacZ2246和lacZU131分别位于与β-半乳糖苷酶氨基酸23、36和41相对应的位点。缺失突变体lacZM112产生了一种二聚体β-半乳糖苷酶蛋白，该蛋白缺失了天然酶的氨基酸残基23至31。
