focused on intramolecular G‐quadruplexes of three or more G‐quartets. Those composed of
two G‐quartets were only shown to form in single‐stranded oligonucleotides. On the basis of
electrophoresis, DMS footprinting, fluorescence labeling, and photo‐cross‐linking, we
detected the formation of DNA: RNA hybrid G‐quadruplexes (HQs) of two G‐quartets during
the transcription of DNA duplexes. These HQs have a lifetime on the minute scale and are …