bases can form stable quadruplex structures by themselves, and a quadruplex formed entirely from a single strand is called an intramolecular quadruplex.

Depending on how the individual runs of guanine bases are arranged in a bimolecular or intramolecular quadruplex, a quadruplex can adopt one of a number of topologies with varying loop configurations. If all strands of DNA proceed in the same direction, the quadruplex is termed parallel. For intramolecular quadruplexes, this means that any loop regions present must be of the propeller