翻訳と辞書 Words near each other ・ Purim ・ Purim spiel ・ Purim Torah ・ Purin ・ Purina ・ Purina Mills ・ Purina ONE ・ Purine ・ Purine analogue ・ Purine imidazole-ring cyclase ・ Purine metabolism ・ Purine nucleosidase ・ Purine nucleoside phosphorylase ・ Purine nucleoside phosphorylase deficiency ・ Purine nucleotide cycle ・ Purine riboswitch ・ Purine synthesis ・ Purine-nucleoside phosphorylase ・ Purinergic receptor ・ Purinergic signalling ・ Purinergic Signalling (journal) ・ Purington Shale ・ Purinones ・ Purinosome ・ Purinton House ・ Purio ・ Puripanda Appala Swamy ・ Puriri ・ Puriri moth ・ Puriri River Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Purine riboswitch ： ウィキペディア英語版 Purine riboswitch A purine riboswitch is a sequence of ribonucleotides in certain messenger RNA (mRNA) that selectively binds to purine ligands via a natural aptamer domain. This binding causes a conformational change in the mRNA that can affect translation by revealing an expression platform for a downstream gene, or by forming a translation-terminating stem-loop. The ultimate effects of such translational regulation often take action to manage an abundance of the instigating purine, and might produce proteins that facilitate purine metabolism or purine membrane uptake. ==Binding Properties== Purine riboswitches bind to their purine ligands via interactions at a three-way junction formed by junctional helix P1 and hairpin helicies P2 and P3.〔 Associations that a purine makes when it is within this ''binding pocket'' stabilize the three-way junction, and support the ligand-bound conformation of the mRNA molecule. The purine riboswitch can become saturated at concentrations as low as 5 nM, which reflects the need for gene expression to respond quickly and dynamically to changes in purine concentration. Despite the relative similarity of the purine-binding aptamer domain across different purine riboswitches, one binding pocket can still discriminate for a single type of purine ligand with high selectivity.〔 Critical to this sensitivity is a single difference in the secondary structure of ribonucleotides: in position 74 of the aptamer domain, it has been found that conversion of a cytosine to a uracil changes an aptamer from being guanine sensitive to being adenine sensitive, and vice versa.〔 Such a conversion is owed to the ability of a nucleotide in position 74 to Watson-Crick base pair with the ligand in the binding pocket, and cytosine and uracil's respective ability to preferentially hydrogen-bond with guanine or adenine.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Purine riboswitch」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.