Transposons (also called transposable elements) 1 are able to "jump" through transposition to different locations within or between genomes, and mainly include insertion sequences (ISs, also called simple transposons), IS-based transposition units, composite transposons, miniature inverted-repeat transposable element (MITE)-flanking transposition units, MITE-like transposition units, unit transposons, integrative and conjugative elements (ICEs, also called conjugative transposons) and integrative and mobilizable elements (IMEs, also called mobilizable transposons). Transposons encode two major kinds of recombinases: (i) transposases or integrases or excisionases responsible for integration and excision, and (ii) resolvases responsible for resolution. Transposons may or may not be bracketed with short direct repeats (DRs), which represent target site duplication signals for transposition.
1. Roberts AP, Chandler M, Courvalin P et al. Revised nomenclature for transposable genetic elements. Plasmid 2008; 60: 167-73.