Polymerization and depolymerization of actin with nucleotide states at filament ends

Ikuko Fujiwara, Shuichi Takeda, Toshiro Oda, Hajime Honda, Akihiro Narita, Yuichiro Maéda

Research output: Contribution to journalReview articlepeer-review

10 Citations (Scopus)


Polymerization induces hydrolysis of ATP bound to actin, followed by γ-phosphate release, which helps advance the disassembly of actin filaments into ADP-G-actin. Mechanical understanding of this correlation between actin assembly and ATP hydrolysis has been an object of intensive studies in biochemistry and structural biology for many decades. Although actin polymerization and depolymerization occur only at either the barbed or pointed ends and the kinetic and equilibrium properties are substantially different from each other, characterizing their properties is difficult to do by bulk assays, as these assays report the average of all actin filaments in solution and are therefore not able to discern the properties of individual actin filaments. Biochemical studies of actin polymerization and hydrolysis were hampered by these inherent properties of actin filaments. Total internal reflection fluorescence (TIRF) microscopy overcame this problem by observing single actin filaments. With TIRF, we now know not only that each end has distinct properties, but also that the rate of γ-phosphate release is much faster from the terminals than from the interior of actin filaments. The rate of γ-phosphate release from actin filament ends is even more accelerated when latrunculin A is bound. These findings highlight the importance of resolving structural differences between actin molecules in the interior of the filament and those at either filament end. This review provides a history of observing actin filaments under light microscopy, an overview of dynamic properties of ATP hydrolysis at the end of actin filament, and structural views of γ-phosphate release.

Original languageEnglish
Pages (from-to)1513-1519
Number of pages7
JournalBiophysical Reviews
Issue number6
Publication statusPublished - Dec 1 2018
Externally publishedYes


  • ATP hydrolysis
  • Phosphate (Pi) release
  • Single actin filament observation
  • TIRF

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Molecular Biology


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