FIG. 3.

The specificity of TnI SURE can be redirected toward fast fibers by swapping 5′ sequences of SURE and FIRE. (A) Slow muscle specificity of wild-type SURE. Normalized luciferase values for slow and fast muscles are shown for three transgenic lines expressing the wild-type TnIs95.SURE construct. Samples were prepared and assayed as described for Fig. 2. (B) Fast muscle specificity of the chimeric FIRE-SURE enhancer. Founders of seven transgenic lines expressing the chimeric TnIs95.FIRE-SURE construct were analyzed for reporter activity.