Fig. 1. Mu transpososome assembly with short DNA fragments. Steps involved in assembly of the stable synaptic complex (SSC). First, each protein component binds to its cognate binding sites on the DNA substrate. These protein-bound DNA segments will associate with each other to form transient higher order complexes. In the absence of the IAS, the paired complex LR would form, but its conversion to the SSC is inefficient. RR complexes and LL complexes would also form. In the presence of the IAS, the LER complex in which both L- and R-ends and the IAS are held together by MuA is formed. This complex is considered to be an efficient precursor to the SSC. In the presence of Mg²⁺, both Mu ends are cleaved by MuA to generate the cleaved donor complex (CDC). In addition to MuA, HU and IHF are required. See the text for details.