FIGURE 1.

General targeting strategy to flox exon 2 of the murine Egr1 gene. (a) The schematic displays the overall structural organization of the mouse Egr1 gene and EGR1 protein (http://useast.ensembl.org and https://www.uniprot.org/uniprotkb/Q544D6/entry). Located on mouse chromosome 18, the Egr1 gene is comprised of two exons, in which exon 1 encodes ~30% of the protein that includes the initiating ATG and the activation 1 (A1) domain. Exon 2 encodes the remainder of the protein, which contains activation domains 2-4 (A2-4) as well as the DNA binding domain with its three zinc finger (ZF) motifs. (b) For effective ablation of EGR1 protein expression by cre-mediated excision in the mouse, exon 2 was chosen to be floxed by 5’ and 3’ LoxP sites using a CRISPR/Cas9 mediated targeting strategy; note: exon 2 of the Egr1 gene in the Egr1^KO mouse was ablated by the Milbrandt group (Lee et al., 1996; Lee et al., 1995).