Table 2.

Major features of prokaryote IS families

FamilyGroup(s)Size range (bp)aDR (bp)bENDScIRdNo. of ORFseCommentsf
IS1   7709 (8–11)GGTY2Phage λ integrase?
IS3 IS2 1,300–1,3505TGAY2DD(35)E
IS3 1,200–1,3003 (4)2
IS51 1,300–1,4003 (4)2
IS150 1,400–1,5503–52
IS407 1,200–1,25042
IS4 1,300–1,9509–12C(A)Y1DDE
IS5 IS5 1,100–1,3504GGY1DDE
IS427 800–1,0002–3Ga/g2
IS903 1,000–1,1009GGC1
IS1031 850–9503GAG1
ISH1 900–1,15081
ISL2 800–1,1002–31
IS6 750–9008GGY1DD(34)E
IS21 1,950–2,5004 (5, 8)TGY2DDE
IS30 1,000–1,2502–3Y1DD(33)E
IS66 2,500–2,7008GTAY>3
IS91 1,500–1,8500N1ssDNA Rep
IS110 1,200–1,5500N1Site-specific recombinase
IS200/IS605 700–2,0000N1 (2)Complex organization
IS256 1,300–1,5008–9Gg/aY1DDE, eukaryotic relatives
IS630 1,100–1,2002Y1DDE, eukaryotic relatives
IS982 1,000NDg ACY1DDE
IS1380 1,6504Cc/gY1
ISAs1 1,200–1,3508CY1
ISL3 1,300–1,5508GGY1
  • a Size range represents the typical range of each group.

  • b Length of direct target repeats. Less frequently observed lengths are included in parentheses.

  • c Conserved terminal base pairs. Capital leters (and capital letters within parentheses) refer to mostly (and often) conserved bases. Lowercase letters separated by slashes indicate alternative conservation at that position.

  • d Presence (Y) or absence (N) of terminal inverted repeats.

  • e ORF, open reading frame. Number in parentheses indicates the possible involvement of a second ORF in the transposition process.

  • f DDE represents the common acidic triad presumed to be part of the active site of the transposase. ssDNA, single-stranded DNA.

  • g ND, not determined.