IS4 is found between eleven or twelve base pair duplications

Abstract
Three mutations caused by the integration of IS4 in galT in both possible orientations were shown by DNA sequence analysis to be integrated between a duplication of eleven base pairs of gene galT. IS4 has been cloned from its single position on the E. coli K12 chromosome. Here, 12 base pairs are duplicated adjacent to IS4. This sequence is unrelated to the duplicated sequence in galT.