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GTP hydrolysis during microtubule assembly.

Publication ,  Journal Article
O'Brien, ET; Voter, WA; Erickson, HP
Published in: Biochemistry
June 30, 1987

The GTP cap model of dynamic instability [Mitchison, T., & Kirschner, M.W. (1984) Nature (London) 312, 237] postulates that a GTP cap at the end of most microtubules stabilizes the polymer and allows continuing assembly of GTP-tubulin subunits while microtubules without a cap rapidly disassemble. This attractive explanation for observed microtubule behavior is based on the suggestion that hydrolysis of GTP is not coupled to assembly but rather takes place as a first-order reaction after a subunit is assembled onto a polymer end. Carlier and Pantaloni [Carlier, M., & Pantaloni, D. (1981) Biochemistry 20, 1918] reported a lag of hydrolysis behind microtubule assembly and a first-order rate constant for hydrolysis (kh) of 0.25/min. A lag has not been demonstrated by other investigators, and a kh value that specifies such a slow rate of hydrolysis is difficult to reconcile with reported steady-state microtubule growth rates and frequencies of disassembly. We have looked for a lag using tubulin free of microtubule-associated protein at concentrations of 18.5-74 microM, assembly with and without glycerol, and two independent assays of GTP hydrolysis. No lag was observed under any of the conditions employed, with initial rates of hydrolysis increasing in proportion to rates of assembly. If hydrolysis is uncoupled from assembly, we estimate that kh must be at least 2.5/min and could be much greater, a result that we argue may be advantageous to the GTP cap model. We also describe a preliminary model of assembly coupled to hydrolysis that specifies formation and loss of a GTP cap, thus allowing dynamic instability.

Duke Scholars

Published In

Biochemistry

DOI

ISSN

0006-2960

Publication Date

June 30, 1987

Volume

26

Issue

13

Start / End Page

4148 / 4156

Location

United States

Related Subject Headings

  • Tubulin
  • Time Factors
  • Swine
  • Phosphorus Radioisotopes
  • Phosphoric Acids
  • Molybdenum
  • Microtubules
  • Methods
  • Hydrolysis
  • Guanosine Triphosphate
 

Citation

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O’Brien, E. T., Voter, W. A., & Erickson, H. P. (1987). GTP hydrolysis during microtubule assembly. Biochemistry, 26(13), 4148–4156. https://doi.org/10.1021/bi00387a061
O’Brien, E. T., W. A. Voter, and H. P. Erickson. “GTP hydrolysis during microtubule assembly.Biochemistry 26, no. 13 (June 30, 1987): 4148–56. https://doi.org/10.1021/bi00387a061.
O’Brien ET, Voter WA, Erickson HP. GTP hydrolysis during microtubule assembly. Biochemistry. 1987 Jun 30;26(13):4148–56.
O’Brien, E. T., et al. “GTP hydrolysis during microtubule assembly.Biochemistry, vol. 26, no. 13, June 1987, pp. 4148–56. Pubmed, doi:10.1021/bi00387a061.
O’Brien ET, Voter WA, Erickson HP. GTP hydrolysis during microtubule assembly. Biochemistry. 1987 Jun 30;26(13):4148–4156.
Journal cover image

Published In

Biochemistry

DOI

ISSN

0006-2960

Publication Date

June 30, 1987

Volume

26

Issue

13

Start / End Page

4148 / 4156

Location

United States

Related Subject Headings

  • Tubulin
  • Time Factors
  • Swine
  • Phosphorus Radioisotopes
  • Phosphoric Acids
  • Molybdenum
  • Microtubules
  • Methods
  • Hydrolysis
  • Guanosine Triphosphate