Gt(ROSA)26Sor^{tm1(CAG-tdTomato*,-EGFP*)Ees}

The nT-nG targeting vector was made by modifying the Rosa26 mT/mG plasmid (see JAX Stock No. 007676). Modifications replaced the N-terminal membrane-targeting domains of tdTomato and EGFP with strong start codons, and added sequences at the C-termini of tdTomato and EGFP that encode amino acids 300-350 of the SRm160 nuclear assembly domain (to direct the stable integration of each fluorescent protein into the nucleus). The final nT-nG targeting vector contained (from 5' to 3') a CMV enhancer/chicken beta-actin core promoter (pCA), a loxP site, the nT cassette (tdTomato protein sequence [non-oligomerizing DsRed variant with a 12 residue linker fusing two copies of the protein (tandem dimer)] with C-terminal SRm160 nuclear targeting signal and a polyadenylation signal), a second loxP site, the nG cassette (an enhanced green fluorescent protein [EGFP] sequence with C-terminal SRm160 nuclear targeting signal and a polyadenylation signal), and an frt-flanked neo cassette. The SRm160 sequences attached to tdTomato and EGFP contain different synonymous mutations (and the SRm160 sequence in tdTomato also has a single non-synonymous mutation) to avoid potential homologous recombination in bacteria between the SRm160 sequences in the nT cassette and nG cassette. (J:199711, J:201735)