Abstract Background Guanine-rich nucleic acid sequences are capable of folding into an intramolecular four-stranded structure called a G-quadruplex. When found in gene promoter regions. G-quadruplexes can downregulate gene expression. possibly by blocking the transcriptional machinery. https://www.roneverhart.com/Neumann-KK-205-Supercardioid-Capsule-Head-Black-008654-p29875/