Excision model for minute- Mos1. (a) Minute transposon structure: the positive DNA strand is indicated by a thin line, and the negative one by a bold line. The transferred and non-transferred strands are represented by red and blue lines respectively, on each inverted repeat. The duplicated TA dinucleotide at the insertion site was located on both strands. (b) Binding of one MOS1 dimer to each ITR bends it at an angle of about 90°. (c) In agreement with the data reported here, cleavages occurred at the inner extremities of both ITRs on the transferred strands. In accordance with previously published data, cleavages occurred at the outer extremities of the ITR, on the non-transferred strands. (d) The single strand nicks at both inner extremities of the ITR allocated flexibility to both non-nicked strands, thus allowing 180° flipping, and the PEC2 assembly. Full excision of the transposon occurred after the second cleavages at the extremity of both ITRs.