Cruciforms represent a novel DNA state with unique physical and biolog
ical properties, including the ability to undergo branch migration in
appropriate sequence backgrounds. Recent results establish a preferred
geometry of immobile cruciforms in Mg2+ solution, the rate of branch
migration, and the binding properties of cruciforms for proteins and s
mall molecule ligands. A structure has been determined for three-arm b
ranches with unpaired bases at the branch.