Fig. 7.

Effect on IRES activity when the double loop is changed into a single loop. The mutant (ABD_Mut) and the WT ABD, as well as positive and negative controls, were assessed for their IRES activity by transfecting each of these constructs into H441 cells. Renilla and firefly luciferase activities were determined at 36 h after transfection, as described in materials and methods. The WT ABD activity was set as 1.0. To compare the effect of the single loop in the insertion mutant (ABD_Mut) activity, the relative IRES activities of 2 deletion mutants (Del_5 and Del_6) are included. Original data of both of these deletion mutants are shown in Fig. 5B. Results showed that the level of IRES activity of the ABD_Mut was significantly lower (**P < 0.01) than that of the WT ABD. However, the level of IRES activity of the ABD_Mut was comparable to that of the 2 deletion mutants (Del_5 and Del_6). Experiments were repeated 4 times (n = 4). Each point shows mean + SE.