The structures of the Tol2 transposable element and the minimal Tol2 vector. At the top of the illustration is the 4,682 base pair (bp), full-length Tol2. RNA transcribed from Tol2 that encodes a transposase protein  is shown by lines (exons) and dotted lines (introns). Black boxes and gray boxes represent coding regions and untranslated regions, respectively. Black arrowheads in boxes at both ends indicate 12 bp terminal inverted repeats (TIRs). The lower portion of the figure shows the minimal Tol2 vector with the green fluorescent protein (GFP) expression cassette. The minimal Tol2 vector contains 200 and 150 bp of DNA from the left and right ends, which include TIRs (black arrows) and subterminal regions (open boxes) . The transposon vector can carry a DNA fragment, for example the GFP expression cassette in this figure, between these sequences.