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. 2014 Apr 22;9(4):e95980. doi: 10.1371/journal.pone.0095980

Figure 1. Control of transgene function by the LacO/LacIR system.

Figure 1

(A) Construct used to create Cx40 transgenic mice consists of a modified TIE2 promoter containing LacO transcriptional regulation sites (positions −117, −25 and +67), Cx40 transgene (Cx40Tg), an internal ribosomal entry sequence (IRES), EGFP, PolyA tail and TIE2 Enhancer element. Proteins expressed from this construct are translated separately due to the presence of the IRES sequence. (B) When bred with LacIR mice, expression of the Cx40Tg should be repressed due to binding of the LacIR protein (pink) to the LacO sites incorporated into the TIE2 promoter. (C) In the presence of IPTG (blue circles) LacIR undergoes a conformational change lessening its affinity for the LacO sites and transcription can proceed.