02537nas a2200241   4500008004100000022001400041245005100055210005000106260007300156300001400229490000900243520183400252653001002086653001202096653000902108653001002117653001702127653000802144100002102152700002502173700001802198856007902216       2014                        eng d  a0304-416500aRole of G-quadruplex located at 5 end of mRNAs0 aRole of Gquadruplex located at 5 end of mRNAs  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC  a3503-35100 v18403 a<p>Background: Secondary structures in 5' UTR of mRNAs play a critical role in regulating protein synthesis. Though studies have indicated the role of secondary structure G-quadruplex in translational regulation, position-specific effect of G-quadruplex in naturally occurring mRNAs is still not understood. As a pre-initiation complex recognises 5' cap of the mRNA and scans along the untranslated region (UTR) before initiating translation, the presence of G-quadruplex in 5' region may have a significant contribution in regulating translation. Here, we investigate the role of G-quadruplex located at the 5' end of an mRNA. Methods: Biophysical characterisation of putative G-quadruplexes was performed using UV and CD spectroscopy. Functional implication of G-quadruplex in the context of their location was assessed in cellulo using gRT-PCR and dual luciferase assay system. Results: PG4 sequences in 5' UTR of AICT interacting protein (AKTIP), cathepsin B (CTSB) and forkhead box E3 (FOXE3) mRNAs form G-quadruplex whereas it is unable to form G-quadruplex in apolipoprotein A-I binding protein (APOA1BP). Our results demonstrated diverse roles of G-quadruplex located at 5' end of mRNAs. Though G-quadruplex in AKTIP and CTSB mRNA act as inhibitory modules, it activates translation in FOXE3 mRNA. Conclusions: Our works suggests that G-quadruplex present at the 5' terminal of an mRNA behaves differently in a different gene context. It can activate or inhibit gene expression. General significance: This study demonstrated that it is difficult to predict the role of G-quadruplex on the basis of its position in 5' UTR. The neighbouring nucleotide sequence, the intracellular milieu and the interacting partners might render diverse functions to this secondary structure. (C) 2014 Elsevier B.V. All rights reserved.</p>10aAKTIP10aAPOA1BP10aCTSB10aFOXE310aG-quadruplex10aUTR1 aAgarwala, Prachi1 aPandey, Satyaprakash1 aMaiti, Souvik  uhttps://library.ncl.res.in/content/role-g-quadruplex-located-5-end-mrnas-0