5n5n
From Proteopedia
Cryo-EM structure of tsA201 cell alpha1B and betaI and betaIVb microtubules
Structural highlights
Function[TBB5_HUMAN] 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. [TBA1B_HUMAN] 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. Publication Abstract from PubMedMicrotubules polymerize and depolymerize stochastically, a behavior essential for cell division, motility and differentiation. While many studies advanced our understanding of how microtubule-associated proteins tune microtubule dynamics in trans, we have yet to understand how tubulin genetic diversity regulates microtubule functions. The majority of in vitro dynamics studies are performed with tubulin purified from brain tissue. This preparation is not representative of tubulin found in many cell types. Here we report the 4.2A cryo-EM structure and in vitro dynamics parameters of alpha1B/betaI+betaIVb microtubules assembled from tubulin purified from a human embryonic kidney cell line with isoform composition characteristic of fibroblasts and many immortalized cell lines. We find that these microtubules grow faster and transition to depolymerization less frequently compared to brain microtubules. Cryo-EM reveals that the dynamic ends of alpha1B/betaI+betaIVb microtubules are less tapered and that these tubulin heterodimers display lower curvatures. Interestingly, analysis of EB1 distributions at dynamic ends suggests no differences in GTP cap sizes. Lastly, we show that the addition of recombinant alpha1A/betaIII tubulin, a neuronal isotype overexpressed in many tumors, proportionally tunes the dynamics of alpha1B/betaI+betaIVb microtubules. Our study is an important step towards understanding how tubulin isoform composition tunes microtubule dynamics. Tubulin isoform composition tunes microtubule dynamics.,Vemu A, Atherton J, Spector JO, Moores CA, Roll-Mecak A Mol Biol Cell. 2017 Oct 11. pii: mbc.E17-02-0124. doi: 10.1091/mbc.E17-02-0124. PMID:29021343[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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