Fig. 4.

The addition of antisense and unstructured sequences internal to the anti-ATP aptamer sequence also generates constructs that support E-AB signaling, albeit with varying levels of success. The introduction of a 60 base polythymine sequence (pseudosandwich) is the poorest performing sequence and exhibits very significant sensor-to-sensor variability. Introducing antisense sequences of varying length produce both signal-on and signal-off architectures. Antisense #1, the longest sequence at 28 bases (forming 11 base pairs) produces a modest, but very reproducible, signal-off signal. The shorter antisense sequences (AS2 and AS3) both produce greater signal changes upon ATP addition.