Blue-light labeling uncovers unexpected protein partners of folded DNA structures

DNA can be more than just a double helix. When four strands are folded into a compact bundle, they form a G-quadruplex (G4). These bundles form in guanine-rich regions across the genome, including telomeres at the ends of chromosomes and the control regions of genes, where the proteins that dock onto them help decide which genes are switched on. G4 does not act the same way everywhere. What it does depends on where it forms and which proteins bind to it. This is why understanding the interactions surrounding G4 is so important.