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。

thumb | 400px |Structure of a G-quadruplex. Left: a G-tetrad. Right: an intramolecular G-quadruplex

 註釋 

 參考文獻 










 外部連結 
 Nanopore and Aptamer Biosensor group{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 – 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- a database of G-quadruplexes near RNA processing sites.
 GRS_UTRdb- a database of G-quadruplexes in the UTRs.
 G-quadruplex Resource Site
 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 from Balasubramanian's group.
 QGRS Mapper: a web-based application for predicting G-quadruplexes in nucleotide sequences and NCBI genes 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

Category:DNA