= Transpososome
A <transpososome> is the <nucleoprotein complex> that brings a <transposable element>'s <DNA> ends together with <transposase> during <DNA transposition>. It is an assembled reaction complex, not another name for the free enzyme or for the mobile DNA sequence. Organizing the ends allows chemical reactions at separated positions to be coordinated.
A 2000 <X-ray crystallography> study determined a <Tn5 transposase>–DNA-end complex at $2.3\,\text{Å}$ resolution. Two <protein subunits> bound the end <DNA>, with each DNA end interacting with both subunits. The structure placed the ends in the <active sites> and gave a framework for interpreting cleavage and strand transfer.<Three-dimensional structure of the Tn5 synaptic complex transposition intermediate by D. R. Davies and others>[Abstract, resolution, dimeric assembly and paired-end orientation]{ref}
For an assembly example, two ends bound separately by two enzyme molecules need not constitute the same state as two ends brought into one functional <transpososome>. The first observation establishes binding; the second additionally requires the appropriate organization. A mutant <transposase> might still bind <DNA> while failing to assemble or catalyze a later step. Consequently, a binding assay, an assembly measurement and an insertion assay test different properties. The Tn5 structure illustrates one molecular architecture; the definition does not require every transposition system to use precisely two subunits or the same end geometry.
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