Reichardt L, Kaiser A D
Proc Natl Acad Sci U S A. 1971 Sep;68(9):2185-9. doi: 10.1073/pnas.68.9.2185.
Direct measurements of the intracellular level of lambda repressor have been made by a DNA-filter assay and a radioimmune assay. Transcription of cI, the structural gene for repressor, appears to initiate at two different promoters, prm and pre. Promoter pre is activated during the establishment of lysogeny by the action of cII and cIII proteins at the DNA site cY. Phage mutated in cII, cIII, or cY do not make a normal burst of repressor after infection and do not efficiently lysogenize the cell. Cro product stops repressor synthesis midway in the infective cycle. Promoter prm maintains the repressor level in established lysogens. Delection mapping places it very near the right operator (Or). Prm is activated by repressor bound to the right operator. In the absence of cII or cIII protein, repressor synthesis requires active repressor and only proceeds on genomes able to bind repressor at Or.
通过DNA过滤测定法和放射免疫测定法对λ阻遏物的细胞内水平进行了直接测量。阻遏物的结构基因cI的转录似乎起始于两个不同的启动子，即prm和pre。在溶原建立过程中，通过cII和cIII蛋白在DNA位点cY处的作用，启动子pre被激活。在cII、cIII或cY中发生突变的噬菌体在感染后不会产生正常的阻遏物爆发，也不能有效地使细胞溶原化。Cro产物在感染周期的中途停止阻遏物的合成。启动子prm维持已建立的溶原菌中的阻遏物水平。缺失作图表明它非常靠近右操纵子（Or）。Prm由结合在右操纵子上的阻遏物激活。在没有cII或cIII蛋白的情况下，阻遏物的合成需要活性阻遏物，并且仅在能够在Or处结合阻遏物的基因组上进行。
