G-四联体

**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，將結構分為平行和反平行。

## 註釋

## 參考文獻

* Jiangtao Ren, Jiahai Wang\* , Lei Han, Erkang Wang\*, Jin Wang\*. Kinetically grafting G-qaudruplex onto DNA nanostructure as structure and function encoding via DNA machine. Chem. Commun. 2011, **47**: 10563–10565 [2015-06-19]. （原始內容存檔於 2015-04-20）.
* Johnson JE, Smith JS, Kozak ML, Johnson FB. In vivo veritas: using yeast to probe the biological functions of G-quadruplexes. Biochimie. 2008, **90** (8): 1250–1263 [2015-06-19]. PMC 2585026 . PMID 18331848. doi:10.1016/j.biochi.2008.02.013. （原始內容存檔於 2019-02-07）.
* Huppert JL and Balasubramanian S. Prevalence of quadruplexes in the human genome. NAR. 2005, **33** (9): 2908–2916 [2007-06-20]. PMC 1140081 . PMID 15914667. doi:10.1093/nar/gki609. （原始內容存檔於 2007-05-06）.
* Todd AK, Johnston M, Neidle S. Highly prevalent putative quadruplex sequence motifs in human DNA. NAR. 2005, **33** (9): 2901–2907 [2007-06-20]. PMC 1140077 . PMID 15914666. doi:10.1093/nar/gki553. （原始內容存檔於 2007-05-06）.
* Burge S, Parkinson GN, Hazel P, Todd AK, Neidle S. Quadruplex DNA: sequence, topology and structure. NAR. 2006, **34** (19): 5402–5415 [2007-06-20]. PMC 1636468 . PMID 17012276. doi:10.1093/nar/gkl655. （原始內容存檔於 2008-10-07）.
* Siddiqui-Jain A, Grand CL, Bearss DJ, Hurley LH. Direct evidence for a G-quadruplex in a promoter region and its targeting with a small molecule to repress c-MYC transcription. PNAS. 2002, **99** (18): 11593–8 [2007-06-20]. PMC 129314 . PMID 12195017. doi:10.1073/pnas.182256799. （原始內容存檔於 2007-10-01）.
* Rawal P, Kummarasetti VB, Ravindran J, Kumar N, Halder K, Sharma R, Mukerji M, Das SK, Chowdhury S. Genome-wide prediction of G4 DNA as regulatory motifs: Role in Escherichia coli global regulation. Genome Res. 2006, **16** (5): 644–55 [2007-06-20]. PMC 1457047 . PMID 16651665. doi:10.1101/gr.4508806. （原始內容存檔於 2007-09-12）.
* Xu Hou, Wei Guo, Fan Xia, Fu-Qiang Nie, Hua Dong, Ye Tian, Liping Wen, Lin Wang, Liuxuan Cao, Yang Yang, Jianming Xue, Yanlin Song, Yugang Wang, Dongsheng Liu, and Lei Jiang. A biomimetic potassium responsive nanochannel: G-quadruplex DNA conformational switching in a synthetic nanopore. J. Am. Chem. Soc. 2009, **131** (22): 7800–7805 [2015-06-19]. PMID 19435350. doi:10.1021/ja901574c. （原始內容存檔於 2022-03-15）.
* Neidle & Balasubramanian (編). Quadruplex Nucleic Acids. 2006 [2007-06-20]. ISBN0-85404-374-8. （原始內容存檔於 2007-09-30）.

## 外部連結

* Nanopore and Aptamer Biosensor group（頁面存檔備份，存於網際網路檔案館）{NAB group}

### 四聯體網站

* COST MP0802 Quadruplex Network – the European network of G-quadruplex community: From first principles to applications
* Quadruplex.org – a website to serve the quadruplex community
* G-Quadruplex World（頁面存檔備份，存於網際網路檔案館） – a website to discuss publications and other information of interest to those working in the field of G-quadruplexes
* Quadbase – downloadable data on predicted G-quadruplexes
* Greglist – a database listing potential G-quadruplex regulated genes
* Database on Quadruplex information: QuadBase from IGIB
* GRSDB（頁面存檔備份，存於網際網路檔案館）- a database of G-quadruplexes near RNA processing sites.
* GRS\_UTRdb- a database of G-quadruplexes in the UTRs.
* G-quadruplex Resource Site（頁面存檔備份，存於網際網路檔案館）
* 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

* Quadparser: Downloadable program for finding putative quadruplex-forming sequences（頁面存檔備份，存於網際網路檔案館） from Balasubramanian's group.
* QGRS Mapper: a web-based application for predicting G-quadruplexes in nucleotide sequences and NCBI genes（頁面存檔備份，存於網際網路檔案館） from Bagga's group.
* Quadfinder: Tool for Prediction and Analysis of G Quadruplex Motifs in DNA/RNA Sequences from Maiti's group, IGIB, Delhi, India