6wvr

<table><tr><td colspan='2'>[[6wvr]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6WVR OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=6WVR FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GDP:GUANOSINE-5-DIPHOSPHATE'>GDP</scene>, <scene name='pdbligand=GTP:GUANOSINE-5-TRIPHOSPHATE'>GTP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=TA1:TAXOL'>TA1</scene></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=6wvr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6wvr OCA], [http://pdbe.org/6wvr PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6wvr RCSB], [http://www.ebi.ac.uk/pdbsum/6wvr PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6wvr ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/TBA1B_BOVIN TBA1B_BOVIN]] Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non-exchangeable site on the alpha chain. [[http://www.uniprot.org/uniprot/E1BJB1_BOVIN E1BJB1_BOVIN]] Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non-exchangeable site on the alpha chain.[RuleBase:RU000352][SAAS:SAAS00031082]

Microtubules are tubular polymers with essential roles in numerous cellular activities. Structures of microtubules have been captured at increasing resolution by cryo-EM. However, dynamic properties of the microtubule are key to its function, and this behavior has proved difficult to characterize at a structural level due to limitations in existing structure determination methods. We developed a high-resolution cryo-EM refinement method that divides an imaged microtubule into its constituent protofilaments, enabling deviations from helicity and other sources of heterogeneity to be quantified and corrected for at the single-subunit level. We demonstrate that this method improves the resolution of microtubule 3D reconstructions and substantially reduces anisotropic blurring artifacts, compared with methods that utilize helical symmetry averaging. Moreover, we identified an unexpected, discrete behavior of the m-loop, which mediates lateral interactions between neighboring protofilaments and acts as a flexible hinge between them. The hinge angle adopts preferred values corresponding to distinct conformations of the m-loop that are incompatible with helical symmetry. These hinge angles fluctuate in a stochastic manner, and perfectly cylindrical microtubule conformations are thus energetically and entropically penalized. The hinge angle can diverge further from helical symmetry at the microtubule seam, generating a subpopulation of highly distorted microtubules. However, the seam-distorted subpopulation disappears in the presence of Taxol, a microtubule stabilizing agent. These observations provide clues into the structural origins of microtubule flexibility and dynamics and highlight the role of structural polymorphism in defining microtubule behavior.

 

== References ==

[[Category: Cha, M]]

[[Category: Debs, G E]]

[[Category: Huehn, A R]]

[[Category: Sindelar, C V]]

[[Category: Structural protein]]