[The Detections, functions and regulations of G-quadruplex]

G-quadruplex structure was found recently as a special secondary structure of Nucleic acid. It can be formed easily and widely in vivo and has important biological functions. Researchers have detected the formation of G-quadruplex in vitro and solved its crystal structure by using specific fluorescent probes, antibodies, etc., which are constantly discovered or synthesized. G-quadruplex structures are distributed widely not only in the significantly functional region as telomere, promoter, gene extron, but also in the 5 'untranslated region (5'UTR), intron and 3'flanking region (3'UTR) of RNA. They play vital roles in the extension of telomeres, DNA replication, transcription, meiosis, recombination, and otherpivotal life processes. Additionally, they can exert anti-tumor, anti-virus, inhibiting angiogenesis and other important functions. Currently anticancer drugs based on G-quadruplex structure have entered clinical trials and obtained good curative effects. G-quadruplex can be regulated endogenously by the methylation and the interaction with many proteins and stays in a balanced content and morphology. Some exogenous small molecules can also play such regulatory roles. This paper will systematically summarize detection methods, special functions and regulation of G-quadruplex in the fields of chemistry, biology and medicine.