The four-stranded DNA structure formed by guanine-rich sequences is called a G-quadruplex.
In a G-quadruplex, four guanine bases associate through Hoogsteen hydrogen bonding to make a roughly square unit called a G-tetrad, or G-quartet. Several tetrads can stack on one another, producing a compact four-stranded structure. A positively charged ion, especially potassium, often sits in the central channel and helps stabilize the stack.
A G-quadruplex does not always require four separate DNA molecules. It can form within one folded strand, between two strands, or from four strands, depending on the sequence and folding pattern. This is why “four-stranded” describes the structure’s topology, not necessarily the number of original DNA molecules involved.
G-quadruplex-forming sequences are especially common in telomeres, the guanine-rich chromosome ends, and have also been identified near gene promoters. They can influence replication, transcription, and genome stability. The structures were recognized in guanine-rich materials decades ago, while modern research has focused on their possible cellular roles and their interaction with helicases and regulatory proteins. “G-triplex” and “G-helix” are not the standard names for this structure.