PiggyBac revertible gene-trap vectors, PBGTV1 and PBGTV2. (A) The PBGTV1 series contain the minimal PB terminal DNA repeats and an adenovirus splice acceptor (SA) Beta-geo gene-trap cassette flanked by FRT sites. Three versions were constructed in which the coding sequence of Beta-geo has different reading frames. (B) The PBGTV2 series contain the minimal PB terminal DNA repeats and a loxP flanked gene-trap cassette consisting of an En2 splice acceptor (En2SA) T2A-Beta-gal-T2A-Neo cassette. Four versions were constructed. In vectors 0, 1, and 2, the coding sequence of T2A-Beta-gal-T2A-Neo has different reading frames. In vector K, an ATG start codon was used for the Beta-gal coding sequence. pA, bovine growth hormone polyA signal; SA, adenovirus major late gene splice acceptor; En2SA, mouse engrailed 2 gene splice acceptor; T2A peptide is a self-cleaving short peptide from Picornavirus (Szymczak et al. 2004).
