User:Andy Maloney/Kinesin & Microtubule Page/Microtubule papers/Tubulin assembly in the presence of calcium ions and taxol microtubule bundling and formation of macrotubule-ring complexes

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These are my notes. Please read the article before reading my notes.


Tubulin assembly in the presence of calcium ions and taxol: microtubule bundling and formation of macrotubule-ring complexes.


  • This paper describes how calcium influences different assemblies of microtubules when they are polymerized in the presence of calcium.
  • They state that protofilaments are about 5 nm in width.
  • Ohhh, reference to glycerol changing the hydrate shell of proteins!
  • Tubulin from porcine brains.
  • Polymerization of tubulin was done in:
    • 2.5 mg/mL tubulin
    • 20 mM Morpholinethane sulfonic acid
    • 80 mM NaCl
    • 1 mM EGTA
    • 0.5 mM MgCl2
    • 0.36 mM GTP
    • 10 µM Taxol
    • pH 6.4
    • Calcium was added either before polymerization or after.
  • They did not see odd microtubule structures in the presence of calcium without Taxol.
    • When incubated at 0˚C with Taxol and then polymerized with 2-30 mM calcium, bundles occurred. This is reminiscent of funky structures that can arise from Taxol discussed in this paper.
    • When incubated with calcium and then polymerized in Taxol, they saw "macrotubules". These macrotubules were sometimes not fully structured, i.e. they had holes or gaps in them.
  • There is an awesome picture of a coiled protofilament.
  • Calcium prevents both lateral microtubule assembly and longitudinal tubulin-tubulin dimer assembly.