分子生物学
大肠杆菌
基因
生物
基因表达
β-半乳糖苷酶
酶
作者
Arthur B. Pardee,François Jacob,Jacques Monod
出处
期刊:Elsevier eBooks
[Elsevier]
日期:1978-01-01
卷期号:: 390-403
标识
DOI:10.1016/b978-0-12-460482-7.50034-8
摘要
A number of extremely closely linked mutations have been found to affect the synthesis of β -galactosidase in E. coli . Some of these ( z mutations) are expressed by loss of the capacity to synthesize active enzyme. Others ( i mutations) allow the enzyme to be synthesized constitutively instead of inducibly as in the wild type. The study of galactosidase synthesis in heteromerozygotes of E. coli indicates that the z and i mutations belong to different cistrons. Moreover the constitutive allele of the i cistron is recessive over the inducible allele. The kinetics of expression of the i + (inducible) character suggest that the i gene controls the synthesis of a specific substance which represses the synthesis of ( β -galactosidase. The constitutive state results from loss of the capacity to synthesize active repressor.
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