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| | <SX load='3jam' size='340' side='right' viewer='molstar' caption='[[3jam]], [[Resolution|resolution]] 3.46Å' scene=''> | | <SX load='3jam' size='340' side='right' viewer='molstar' caption='[[3jam]], [[Resolution|resolution]] 3.46Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[3jam]] is a 37 chain structure with sequence from [https://en.wikipedia.org/wiki/Atcc_56498 Atcc 56498] and [https://en.wikipedia.org/wiki/Kluyveromyces_lactis Kluyveromyces lactis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3JAM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3JAM FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[3jam]] is a 10 chain structure with sequence from [https://en.wikipedia.org/wiki/Kluyveromyces_lactis Kluyveromyces lactis] and [https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3JAM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3JAM FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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]] 3.46Å</td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[3j80|3j80]], [[3jap|3jap]], [[3jaq|3jaq]]</div></td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></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=3jam FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3jam OCA], [https://pdbe.org/3jam PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3jam RCSB], [https://www.ebi.ac.uk/pdbsum/3jam PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3jam ProSAT]</span></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=3jam FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3jam OCA], [https://pdbe.org/3jam PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3jam RCSB], [https://www.ebi.ac.uk/pdbsum/3jam PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3jam ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[https://www.uniprot.org/uniprot/RS27A_KLULA RS27A_KLULA]] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, and DNA-damage responses. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling (By similarity). Ribosomal protein S27a is a component of the 40S subunit of the ribosome. [[https://www.uniprot.org/uniprot/RSSA_KLULA RSSA_KLULA]] Required for the assembly and/or stability of the 40S ribosomal subunit. Required for the processing of the 20S rRNA-precursor to mature 18S rRNA in a late step of the maturation of 40S ribosomal subunits. [[https://www.uniprot.org/uniprot/RS21_KLULA RS21_KLULA]] Required for the processing of the 20S rRNA-precursor to mature 18S rRNA in a late step of the maturation of 40S ribosomal subunits. Has a physiological role leading to 18S rRNA stability (By similarity). [[https://www.uniprot.org/uniprot/IF1A_YEAST IF1A_YEAST]] Seems to be required for maximal rate of protein biosynthesis. Enhances ribosome dissociation into subunits and stabilizes the binding of the initiator Met-tRNA(I) to 40 S ribosomal subunits. [[https://www.uniprot.org/uniprot/SUI1_YEAST SUI1_YEAST]] Additional factor that functions in concert with eIF-2 and the initiator tRNA in directing the ribosome to the proper start site of translation.
| + | [https://www.uniprot.org/uniprot/IF1A_YEAST IF1A_YEAST] Seems to be required for maximal rate of protein biosynthesis. Enhances ribosome dissociation into subunits and stabilizes the binding of the initiator Met-tRNA(I) to 40 S ribosomal subunits. |
| - | <div style="background-color:#fffaf0;">
| + | |
| - | == Publication Abstract from PubMed ==
| + | |
| - | Translation initiation in eukaryotes begins with the formation of a pre-initiation complex (PIC) containing the 40S ribosomal subunit, eIF1, eIF1A, eIF3, ternary complex (eIF2-GTP-Met-tRNAi), and eIF5. The PIC, in an open conformation, attaches to the 5' end of the mRNA and scans to locate the start codon, whereupon it closes to arrest scanning. We present single particle cryo-electron microscopy (cryo-EM) reconstructions of 48S PICs from yeast in these open and closed states, at 6.0 A and 4.9 A, respectively. These reconstructions show eIF2beta as well as a configuration of eIF3 that appears to encircle the 40S, occupying part of the subunit interface. Comparison of the complexes reveals a large conformational change in the 40S head from an open mRNA latch conformation to a closed one that constricts the mRNA entry channel and narrows the P site to enclose tRNAi, thus elucidating key events in start codon recognition.
| + | |
| - | | + | |
| - | Conformational Differences between Open and Closed States of the Eukaryotic Translation Initiation Complex.,Llacer JL, Hussain T, Marler L, Aitken CE, Thakur A, Lorsch JR, Hinnebusch AG, Ramakrishnan V Mol Cell. 2015 Aug 6;59(3):399-412. doi: 10.1016/j.molcel.2015.06.033. Epub 2015 , Jul 23. PMID:26212456<ref>PMID:26212456</ref>
| + | |
| - | | + | |
| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
| + | |
| - | </div>
| + | |
| - | <div class="pdbe-citations 3jam" style="background-color:#fffaf0;"></div>
| + | |
| - | == References ==
| + | |
| - | <references/>
| + | |
| | __TOC__ | | __TOC__ |
| | </SX> | | </SX> |
| - | [[Category: Atcc 56498]] | |
| | [[Category: Kluyveromyces lactis]] | | [[Category: Kluyveromyces lactis]] |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| - | [[Category: Hussain, T]] | + | [[Category: Saccharomyces cerevisiae]] |
| - | [[Category: Llacer, J L]] | + | [[Category: Hussain T]] |
| - | [[Category: Ramakrishnan, V]] | + | [[Category: Llacer JL]] |
| - | [[Category: Eukaryotic translation initiation]] | + | [[Category: Ramakrishnan V]] |
| - | [[Category: Small ribosome subunit]]
| + | |
| - | [[Category: Translation]]
| + | |
