Transposition of some transposable elements occurs by a replicative mechanism. Jim Shapiro proposed a model that describes the basic mechanism of replicative transposition. The Shapiro model is shown in the following figure.
Some transposable elements that use the replicative mechanism include Tn3, IS1000, and related transposons. An essential feature of this model is that a cointegrate is an intermediate in the transposition process. It is possible to take advantage of the cointegrate to select for insertions even when there is no easily selectable marker on the transposable element itself, as shown in the following cartoon.
Shapiro, J. 1979. Molecular model for the transposition and replication of bacteriophage Mu and other transposable elements. Proc. Natl. Acad. Sci. USA 76:1933-1937.
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Last modified October 14, 2003