Class I Transposable Elements

Class I elements (Figure 25.35) encode a transposase but not a resolvase, and are of two types. The simplest is called an insertion sequence (IS), which consists simply of a gene for transposase, flanked by two short inverted repeat sequences of about 15 to 25 base pairs. A less simple structure, called a composite transposon, consists of a protein-encoding gene, such as a gene conferring antibiotic resistance, flanked by two insertion sequences, or IS-like elements. These elements may be in either identical or inverted orientations.

See also: Transposable Genetic Elements Recombination, Site-Specific Recombination, Gene Rearrangements, Table 25.4