During pronuclear injection a construct with the promoter of choise that is connected with the protein coding region (a gene or cDNA) is integrated in random position of the mouse genome. The TG mice produced contain single or multiple copies of the transgene.
The technique is availble aslo for long ( >100 kbp-long) BAC transgenes.
For more precise control of the transgne expression the transgene can be introduced a well characterized, transcriptionally active locus, such as Rosa26.
TCDM holds construct backbones for prducing transgenic mice with Cre-activated transgene expression. The method relies on a “Stop-casette” hindering the transgene expresion that is revovable by Cre-recombinase in doulbe-transgenic mice.