Patent ID: 7521546

Claim:
A branched or multichain nucleic acid switch adapted to switch from a first conformation to a second conformation upon ligand binding, said switch comprising: a probe strand P comprising a ligand binding domain; a switching framework comprising a cover strand (C), which is partially but not completely complementary to P; a tether that holds P and C together while the switch changes between the first and second conformations without dissociating the branched or multichain nucleic acid thereby creating a rapidly reversible switch; a toggle strand (T) tethered to the P-strand and the C-strand by covalent linkage; and a signaling apparatus comprising a combination of signaling entities, wherein a ligand for the ligand binding domain is selected from the group consisting of proteins, cell-surface features, and small molecules, and wherein the ligand binding domain is sequestered in the first conformation.