Figure 43-4: Plasmid pLT7K and its use. An illustration of the use of pLT7K to clone a gene (R) specifying a restriction endonuclease in the absence of its cognate modification enzyme. At 37°C in the absence of IPTG the Lac repressor binds to the lac operator, and transcription from the T7 promoter is minimal; the λ temperature-sensitive repressor is inactivated, and transcription from pR antagonizes any residual transcription of gene R from the T7 promoter. At 30°C, in the presence of IPTG, transcription of gene R occurs from the T7 promoter, and transcription from pR, the opposing promoter, is repressed. This figure is taken with permission from Kong et al. (44). (for better image quality, click here for tif image, which may be quite large; may also require screen refreshing plus special software to view; or view larger tif in separate window)

Figure 43-1, Figure 43-2, Figure 43-3, Figure 43-4

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