Structural plugs at microtubule ends may regulate polymer dynamics in vitro

S. Azhar, D. B. Murphy

Research output: Contribution to journalArticle

Abstract

Microtubules contain in their lumens distinct structures (plugs) that influence their dynamic behavior in vitro. As observed by electron microscopy, plugs are stain-occluding structures 10-30 nm in length that occur along the lengths and at the ends of microtubules. Plugs occur at a frequency of 20-40% at the ends of microtubules assembled from cycled microtubule protein containing MAPs. While the composition of plugs is not known, preliminary evidence suggests that they are accretions of tubulin, that they are labile, and that they are more common in preparations containing MAPs. When polymers are induced to depolymerize by endwise subunit dissociation, the frequency of plugged microtubule ends increases transiently, suggesting that plugs temporarily stabilize microtubules. The functional significance of plugs may be that they prevent the sudden complete loss of microtubules through catastrophic disassembly. It is possible that plugs, by slowing the rate of disassembly, enable a polymer to add GTP-tubulin subunits, thereby forming a stabilizing GTP-cap. These observations suggest that plugs may stabilize polymers and account for the frequent transitions from shortening to growing phases that characterize dynamic instability.

Original languageEnglish (US)
Pages (from-to)156-161
Number of pages6
JournalCell Motility and the Cytoskeleton
Volume15
Issue number3
DOIs
StatePublished - 1990

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Microtubules
Polymers
Tubulin
Guanosine Triphosphate
Microtubule Proteins
In Vitro Techniques
Electron Microscopy
Coloring Agents

ASJC Scopus subject areas

  • Cell Biology

Cite this

Structural plugs at microtubule ends may regulate polymer dynamics in vitro. / Azhar, S.; Murphy, D. B.

In: Cell Motility and the Cytoskeleton, Vol. 15, No. 3, 1990, p. 156-161.

Research output: Contribution to journalArticle

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