FIG. 4.

Transposition assay results of strains with deletions in the U5-IR structure. (A) Arrows indicate the positions of the deletions. Nucleotides left of the arrows are deleted. Deletion 1 resulted in the formation of a 14-nt loop. Deletion 2 resulted in the formation of a 6-nt loop. Deletion 3 eliminated the U5-IR stem-loop. (B) Growth on G418-containing plates indicates transposition activity. The extent of growth on the G418-containing plate is a direct measure of transposition activity. WT, strain with a wild-type version of Tf1.