Skip to main content
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1982 Jan;79(2):490–494. doi: 10.1073/pnas.79.2.490

Subunit treadmilling of microtubules or actin in the presence of cellular barriers: possible conversion of chemical free energy into mechanical work.

T L Hill, M W Kirschner
PMCID: PMC345769  PMID: 6952202

Abstract

Free microtubule or actin filaments, along with the monomeric forms of the protein, hydrolyze GTP or ATP to produce a flux of subunits through the polymer. This flux, called treadmilling, produces no useful work. In the cell, however, these filaments are likely to be constrained between nucleating sites and other barriers that will limit polymer growth. We study here the effects of a small compression of the filaments resulting from polymerization against such barriers. If subunits can still exchange at the two ends, treadmilling will take place here as well. Under these conditions, the filament system can do useful work. The free energy of NTP hydrolysis can be used to transport materials, attached to the filament, against a resisting force. This process can in principle take place at high efficiency and bears a resemblance in a bioenergetic sense to the utilization of ATP free energy in muscle contraction. The same general principles apply to a polymer in which one end is anchored and one end is free.

Full text

PDF
490

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bergen L. G., Borisy G. G. Head-to-tail polymerization of microtubules in vitro. Electron microscope analysis of seeded assembly. J Cell Biol. 1980 Jan;84(1):141–150. doi: 10.1083/jcb.84.1.141. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Eisenberg E., Hill T. L., Chen Y. Cross-bridge model of muscle contraction. Quantitative analysis. Biophys J. 1980 Feb;29(2):195–227. doi: 10.1016/S0006-3495(80)85126-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Ferrone F. A., Hofrichter J., Sunshine H. R., Eaton W. A. Kinetic studies on photolysis-induced gelation of sickle cell hemoglobin suggest a new mechanism. Biophys J. 1980 Oct;32(1):361–380. doi: 10.1016/S0006-3495(80)84962-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Hill T. L. Bioenergetic aspects and polymer length distribution in steady-state head-to-tail polymerization of actin or microtubules. Proc Natl Acad Sci U S A. 1980 Aug;77(8):4803–4807. doi: 10.1073/pnas.77.8.4803. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Hill T. L. Microfilament or microtubule assembly or disassembly against a force. Proc Natl Acad Sci U S A. 1981 Sep;78(9):5613–5617. doi: 10.1073/pnas.78.9.5613. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Hill T. L. Steady-state head-to-tail polymerization of actin or microtubules. II. Two-state and three-state kinetic cycles. Biophys J. 1981 Mar;33(3):353–371. doi: 10.1016/S0006-3495(81)84900-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Kirschner M. W. Implications of treadmilling for the stability and polarity of actin and tubulin polymers in vivo. J Cell Biol. 1980 Jul;86(1):330–334. doi: 10.1083/jcb.86.1.330. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Margolis R. L., Wilson L. Addition of colchicine--tubulin complex to microtubule ends: the mechanism of substoichiometric colchicine poisoning. Proc Natl Acad Sci U S A. 1977 Aug;74(8):3466–3470. doi: 10.1073/pnas.74.8.3466. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. NICKLAS R. B. CHROMOSOME VELOCITY DURING MITOSIS AS A FUNCTION OF CHROMOSOME SIZE AND POSITION. J Cell Biol. 1965 Apr;25:SUPPL–SUPPL:135. doi: 10.1083/jcb.25.1.119. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Wegner A. Head to tail polymerization of actin. J Mol Biol. 1976 Nov;108(1):139–150. doi: 10.1016/s0022-2836(76)80100-3. [DOI] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES