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Xenopus laevis as a Model to Identify Translation Impairment
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普遍的な翻訳開始因子IF2/eIF5BのX線構造:GDPとGTPを結合する形状の変化
A Roll-Mecak1, C Cao, T E Dever
1Laboratories of Molecular Biophysics The Rockefeller University 10021, New York, NY 10021, USA.
Cell
|December 15, 2000
まとめ
普遍的な翻訳開始因子IF2/eIF5Bに関する構造的な洞察は,そのカップの形とGTPaseの機能を明らかにします. X線構造は,IF2/eIF5Bがすべての生命体におけるタンパク質合成の重要なステップをどのように促進するかを明らかにしています.
科学分野:
- 分子生物学は分子生物学である.
- 構造生物学 構造生物学とは
- バイオケミストリー バイオケミストリー
背景:
- 普遍的な翻訳開始因子IF2/eIF5Bは,生命の3つの領域すべてでタンパク質合成を開始するために不可欠です.
- リボソームサブユニットを結合させ,イニシアターtRNAがリボソームに結合するのを促進する上で重要な役割を果たします.
研究 の 目的:
- IF2/eIF5B.の機能を支える構造的メカニズムを解明する.
- IF2/eIF5Bの3次元構造を異なる機能状態 (フリー,GDPbound,GTPbound) で決定する.
主な方法:
- 高解像度構造を入手するために,X線結晶学を用いた.
- 比較構造分析を使用して,構造の変化と機能的要素を特定しました.
主要な成果:
- この研究では,IF2/eIF5BのX線構造を,その自由,不活性GDP結合,および活性GTP結合の形態で決定した.
- 保存ドメインアーキテクチャが特定され,N-ターミナルGドメイン,EF-Tu型ベータバレル,新しいアルファ/ベータ/アルファサンドイッチドメインが含まれています.
- 分子レバーメカニズムが明らかにされ,GTP結合部位からタンパク質の遠い領域への構成変化を拡大しました.
結論:
- これらの構造は,IF2/eIF5BのGTPase活性と,リボソーム結合におけるその役割のメカニズム的基礎を提供する.
- この発見は,バクテリア,アルカイア,ユカリオットにおける翻訳開始の普遍的なメカニズムについての洞察を提供します.
関連する概念動画
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Initiation of Translation
Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Initiation of Translation
Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...

