G-四聯體

G-四聯體（英語：G-quadruplex、G-tetrads或G4-DNA）是一種由富含鳥嘌呤的核酸序列所構成的四股型態。含有經由胡斯坦(Hoogsteen)氫鍵維持穩定，並由鳥嘌呤以正方形方式排列而成的結構。在方形中央有一個單價陽離子（通常是鉀）。這種結構可見於DNA、RNA、LNA（鎖核酸）與PNA（肽核酸）；根據形成四聯體的各股的方向，可能有分子內（intramolecular）、雙分子（bimolecular）或四分子（tetramolecular）等不同類型。

在四聯體的結構中，我們可以根據四股的方向，將結構分為平行和。

註釋
參考文獻
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外部連結

• [http://nanopore.weebly.com/ Nanopore and Aptamer Biosensor group]{NAB group}

四聯體網站

• [https://web.archive.org/web/20150619072314/http://www.g4net.org/ COST MP0802 Quadruplex Network] – the European network of G-quadruplex community: From first principles to applications
• [https://web.archive.org/web/20180813180803/http://quadruplex.org/ Quadruplex.org] – a website to serve the quadruplex community
• [http://gquadruplex.wordpress.com/ G-Quadruplex World] – a website to discuss publications and other information of interest to those working in the field of G-quadruplexes
• [https://web.archive.org/web/20080503160223/http://www.quadruplex.org/?view=quadbase Quadbase] – downloadable data on predicted G-quadruplexes
• [https://web.archive.org/web/20071222211113/http://tubic.tju.edu.cn/greglist/ Greglist] – a database listing potential G-quadruplex regulated genes
• [https://web.archive.org/web/20181021091915/http://quadbase.igib.res.in/: Database on Quadruplex information: QuadBase from IGIB]
• [http://bioinformatics.ramapo.edu/GRSDB2/ GRSDB]- a database of G-quadruplexes near RNA processing sites.
• [https://web.archive.org/web/20110720035046/http://bioinformatics.ramapo.edu/GRS_UTRDB/ GRS_UTRdb]- a database of G-quadruplexes in the UTRs.
• [http://bioinformatics.ramapo.edu/GQRS/ G-quadruplex Resource Site]
• [https://web.archive.org/web/20101230025145/http://nonb.abcc.ncifcrf.gov/apps/nBMST/default non-B Motif Search Tool at non-B DB]- a web server to predict G-quadruplex forming motifs and other non-B DNA forming motifs from users' DNA sequences.

預測G-四聯體的工具

• [http://www.quadruplex.org/?view=quadparser_web Quadparser: Downloadable program for finding putative quadruplex-forming sequences] from Balasubramanian's group.
• [http://bioinformatics.ramapo.edu/QGRS/ QGRS Mapper: a web-based application for predicting G-quadruplexes in nucleotide sequences and NCBI genes] from Bagga's group.
• [http://202.54.26.221/quadfinder/ Quadfinder: Tool for Prediction and Analysis of G Quadruplex Motifs in DNA/RNA Sequences from Maiti's group, IGIB, Delhi, India]