transposable genetic element
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transposable genetic element a form of MOBILE GENETIC ELEMENT, being a discrete DNA sequence that can move from one place to another in a GENOME by ‘transposition’. The phenomenon was first reported in the 1950s by Barbara McClintock, who worked on maize. She received a Nobel Prize in 1983 for her discoveries in this area. However, transposable elements have been found in various organisms. Most elements have INVERTED REPEATS at their ends, which are often needed for transposition. Prokaryotic transposable elements are of a number of types including INSERTION SEQUENCES, TRANSPOSONS and transposing BACTERIOPHAGES, for example, Mu. For eukaryotic transposable elements the main distinction is whether they transpose via an RNA intermediate (often called ‘retrotransposons’) or directly from DNA to DNA. Transposable elements can cause MUTATION and their activity can result in rearrangements of the genome. They probably have an important role in the evolution of genomes.