Figure 2.

Binding of transposase to the Minos inverted terminal repeat and internal Minos transcription initiation sites. (a) DNAaseI footprint of a Minos inverted terminal repeat. 'G+A reaction' indicates G and A specific sequence reaction; the DNAaseI protection reactions were done in duplicate. '+ transposase' indicates twofold molar excess of transposase over target DNA, and '++ transposase' indicates 20-fold molar excess of transposase. The positions of the protected sequences (open boxes), the hypersensitive positions (filled box), as well as the positions of the inner (bottom arrow) and outer direct repeats (top arrow) are indicated. Experimental details are available on request. (b) Promoter activity of a Minos inverted terminal repeat. 'A', 'C', 'G', and 'T' indicate base specific sequencing reactions. Also shown are primer extension reactions with a Minos-specific primer on total RNA isolated from D. melanogaster populations with (+) or without (-) a Minos insertion. The lower horizontal arrow indicates a transcription start about 30 base pairs downstream from the inner direct repeat. An additional transcription start site is detected between the two direct repeats (upper horizontal arrow). The vertical arrow and dashed lines indicate the inner direct repeat.