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| | <SX load='6gaw' size='340' side='right' viewer='molstar' caption='[[6gaw]], [[Resolution|resolution]] 3.20Å' scene=''> | | <SX load='6gaw' size='340' side='right' viewer='molstar' caption='[[6gaw]], [[Resolution|resolution]] 3.20Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[6gaw]] is a 95 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human] and [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6GAW OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6GAW FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[6gaw]] is a 16 chain structure with sequence from [https://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6GAW OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6GAW FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=5GP:GUANOSINE-5-MONOPHOSPHATE'>5GP</scene>, <scene name='pdbligand=FME:N-FORMYLMETHIONINE'>FME</scene>, <scene name='pdbligand=GSP:5-GUANOSINE-DIPHOSPHATE-MONOTHIOPHOSPHATE'>GSP</scene>, <scene name='pdbligand=GTP:GUANOSINE-5-TRIPHOSPHATE'>GTP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=SPM:SPERMINE'>SPM</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.2Å</td></tr> |
| - | <tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=UNK:UNKNOWN'>UNK</scene></td></tr>
| + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=5GP:GUANOSINE-5-MONOPHOSPHATE'>5GP</scene>, <scene name='pdbligand=FME:N-FORMYLMETHIONINE'>FME</scene>, <scene name='pdbligand=GSP:5-GUANOSINE-DIPHOSPHATE-MONOTHIOPHOSPHATE'>GSP</scene>, <scene name='pdbligand=GTP:GUANOSINE-5-TRIPHOSPHATE'>GTP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=SPM:SPERMINE'>SPM</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[6gaz|6gaz]], [[6gb2|6gb2]]</td></tr>
| + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6gaw FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6gaw OCA], [https://pdbe.org/6gaw PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6gaw RCSB], [https://www.ebi.ac.uk/pdbsum/6gaw PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6gaw ProSAT]</span></td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">MTIF2 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN])</td></tr>
| + | |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6gaw FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6gaw OCA], [http://pdbe.org/6gaw PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6gaw RCSB], [http://www.ebi.ac.uk/pdbsum/6gaw PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6gaw ProSAT]</span></td></tr> | + | |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/IF2M_HUMAN IF2M_HUMAN]] One of the essential components for the initiation of protein synthesis. Protects formylmethionyl-tRNA from spontaneous hydrolysis and promotes its binding to the 30S ribosomal subunits. Also involved in the hydrolysis of GTP during the formation of the 70S ribosomal complex. | + | [https://www.uniprot.org/uniprot/A0A4X1U6S6_PIG A0A4X1U6S6_PIG] |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
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| | __TOC__ | | __TOC__ |
| | </SX> | | </SX> |
| - | [[Category: Human]] | |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| | [[Category: Sus scrofa]] | | [[Category: Sus scrofa]] |
| - | [[Category: Ban, N]] | + | [[Category: Ban N]] |
| - | [[Category: Boehringer, D]] | + | [[Category: Boehringer D]] |
| - | [[Category: Kummer, E]] | + | [[Category: Kummer E]] |
| - | [[Category: Leibundgut, M]] | + | [[Category: Leibundgut M]] |
| - | [[Category: Initiation factor if2]]
| + | |
| - | [[Category: Membrane targeting]]
| + | |
| - | [[Category: Mitochondria]]
| + | |
| - | [[Category: Ribosome]]
| + | |
| - | [[Category: Translation initiation]]
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| Structural highlights
Function
A0A4X1U6S6_PIG
Publication Abstract from PubMed
Mitochondria maintain their own specialized protein synthesis machinery, which in mammals is used exclusively for the synthesis of the membrane proteins responsible for oxidative phosphorylation(1,2). The initiation of protein synthesis in mitochondria differs substantially from bacterial or cytosolic translation systems. Mitochondrial translation initiation lacks initiation factor 1, which is essential in all other translation systems from bacteria to mammals(3,4). Furthermore, only one type of methionyl transfer RNA (tRNA(Met)) is used for both initiation and elongation(4,5), necessitating that the initiation factor specifically recognizes the formylated version of tRNA(Met) (fMet-tRNA(Met)). Lastly, most mitochondrial mRNAs do not possess 5' leader sequences to promote mRNA binding to the ribosome(2). There is currently little mechanistic insight into mammalian mitochondrial translation initiation, and it is not clear how mRNA engagement, initiator-tRNA recruitment and start-codon selection occur. Here we determine the cryo-EM structure of the complete translation initiation complex from mammalian mitochondria at 3.2 A. We describe the function of an additional domain insertion that is present in the mammalian mitochondrial initiation factor 2 (mtIF2). By closing the decoding centre, this insertion stabilizes the binding of leaderless mRNAs and induces conformational changes in the rRNA nucleotides involved in decoding. We identify unique features of mtIF2 that are required for specific recognition of fMet-tRNA(Met) and regulation of its GTPase activity. Finally, we observe that the ribosomal tunnel in the initiating ribosome is blocked by insertion of the N-terminal portion of mitochondrial protein mL45, which becomes exposed as the ribosome switches to elongation mode and may have an additional role in targeting of mitochondrial ribosomes to the protein-conducting pore in the inner mitochondrial membrane.
Unique features of mammalian mitochondrial translation initiation revealed by cryo-EM.,Kummer E, Leibundgut M, Rackham O, Lee RG, Boehringer D, Filipovska A, Ban N Nature. 2018 Aug;560(7717):263-267. doi: 10.1038/s41586-018-0373-y. Epub 2018 Aug, 8. PMID:30089917[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Kummer E, Leibundgut M, Rackham O, Lee RG, Boehringer D, Filipovska A, Ban N. Unique features of mammalian mitochondrial translation initiation revealed by cryo-EM. Nature. 2018 Aug;560(7717):263-267. doi: 10.1038/s41586-018-0373-y. Epub 2018 Aug, 8. PMID:30089917 doi:http://dx.doi.org/10.1038/s41586-018-0373-y
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