Skip to main content
Journal cover image

Effects of magnesium on the dynamic instability of individual microtubules.

Publication ,  Journal Article
O'Brien, ET; Salmon, ED; Walker, RA; Erickson, HP
Published in: Biochemistry
July 17, 1990

We investigated the effect of magnesium ion (Mg) on the parameters of dynamic instability of individual porcine brain microtubules. Rates of elongation and rapid shortening were measured by using video-enhanced DIC light microscopy and evaluated by using computer-generated plots of microtubule length vs time. Increasing [Mg] from 0.25 to 6 mM increased the second-order association rate constant for elongation about 25% at each end. At plus ends, this resulted in a 1.5-2-fold increase in elongation rates over the tubulin concentrations explored. Rapid shortening rates were more dramatically affected by Mg. As [Mg] was increased from 0.25 to 6 mM, the average rate of rapid shortening increased about 3-fold at plus ends and 4-5-fold at minus ends. The ends had roughly equivalent average rates at low [Mg], of 30-45 microns/min. At any Mg concentration, rates of disassembly varied from one microtubule to another, and often an individual microtubule would exhibit more than one rate during a single shortening phase. Individual rates at 6 mM Mg varied from 12 to 250 microns/min. Over the concentration range explored, Mg affected the frequencies of transition from elongation to shortening and back only at minus ends. Minus ends were relatively stable at low [Mg], having 4 times the frequency of rescue than at high [Mg], and a lower frequency of catastrophe (particularly evident at low tubulin concentrations). Plus ends, surprisingly, were highly unstable at all Mg concentrations investigated, having about the same transition frequencies as did the least stable (high Mg) minus ends. Our results have implications for models of the GTP cap, again emphasizing that GTP caps cannot build up in proportion to elongation rate, and must be constrained to the tips of growing microtubules.

Duke Scholars

Published In

Biochemistry

DOI

ISSN

0006-2960

Publication Date

July 17, 1990

Volume

29

Issue

28

Start / End Page

6648 / 6656

Location

United States

Related Subject Headings

  • Videotape Recording
  • Tubulin
  • Swine
  • Microtubules
  • Magnesium
  • Guanosine Triphosphate
  • Brain Chemistry
  • Biochemistry & Molecular Biology
  • Animals
  • 3404 Medicinal and biomolecular chemistry
 

Citation

APA
Chicago
ICMJE
MLA
NLM
O’Brien, E. T., Salmon, E. D., Walker, R. A., & Erickson, H. P. (1990). Effects of magnesium on the dynamic instability of individual microtubules. Biochemistry, 29(28), 6648–6656. https://doi.org/10.1021/bi00480a014
O’Brien, E. T., E. D. Salmon, R. A. Walker, and H. P. Erickson. “Effects of magnesium on the dynamic instability of individual microtubules.Biochemistry 29, no. 28 (July 17, 1990): 6648–56. https://doi.org/10.1021/bi00480a014.
O’Brien ET, Salmon ED, Walker RA, Erickson HP. Effects of magnesium on the dynamic instability of individual microtubules. Biochemistry. 1990 Jul 17;29(28):6648–56.
O’Brien, E. T., et al. “Effects of magnesium on the dynamic instability of individual microtubules.Biochemistry, vol. 29, no. 28, July 1990, pp. 6648–56. Pubmed, doi:10.1021/bi00480a014.
O’Brien ET, Salmon ED, Walker RA, Erickson HP. Effects of magnesium on the dynamic instability of individual microtubules. Biochemistry. 1990 Jul 17;29(28):6648–6656.
Journal cover image

Published In

Biochemistry

DOI

ISSN

0006-2960

Publication Date

July 17, 1990

Volume

29

Issue

28

Start / End Page

6648 / 6656

Location

United States

Related Subject Headings

  • Videotape Recording
  • Tubulin
  • Swine
  • Microtubules
  • Magnesium
  • Guanosine Triphosphate
  • Brain Chemistry
  • Biochemistry & Molecular Biology
  • Animals
  • 3404 Medicinal and biomolecular chemistry