Alternative mechanisms for transcription regulation by multiplexes. Schematic representations of transcription regulation by multiplexes and multiplex-forming oligonucleotides. A) A multiplex-forming oligonucleotide folds into a structure that serves as an aptamer, which competes for promoter binding by a general transcription factor (center, light gray or yellow). B) A multiplex-forming oligonucleotide binds to an RNA transcript and directs its degradation by RNase H. C) An upstream promoter multiplex binds proteins that actively interfere with the function of specific and general transcription factors.