Comparison of the IS Bmu 23 and IS Bmu 2 insertion sequences. A) Structure of ISBmu 23. IR, inverted repeats. Relative positions of the inverted repeats and transposase gene (in bp) are shown below. B) Alignment of the ISBmu 2 and ISBmu 23 inverted repeats. Non-consensus bases are underlined. ISBmu 2 sequences are from Ohtsubo et al. . L, left repeat; Ri, right repeat inverted.