Leiomodin2 is a polymerase at the pointed ends of actin filaments

Q: What is the clinical evidence from this study?

Study design: Editorial. Intervention: Leiomodin 2 vs. Free pointed ends (no leiomodin 2). Primary outcome: Elongation rate at pointed ends of actin filaments.

Thomas D. Pollard

doi:10.1038/s41467-026-75794-z

July 24, 2026Nature CommunicationsOpen Access

Leiomodin2 is a polymerase at the pointed ends of actin filaments

View Full Paper

Ask AI

Bookmark

Share

Key result

Leiomodin 2 promotes the elongation of actin filaments at their slowly growing pointed ends, plateauing at 1.6 subunits per second at actin monomer concentrations above 2 µM.

Figures

Key Points

To investigate the molecular mechanism by which leiomodin 2 regulates the assembly and dynamics of actin filaments at their pointed ends.
Observed single actin filaments in real time using total internal reflection fluorescence microscopy inside microfluidics flow cells to evaluate elongation and disassembly.
Performed single-particle cryo-electron microscopy classification and reconstruction on short actin filaments assembled with leiomodin 2, capping protein, and tropomyosin at resolutions up to 2.0 Å.
Leiomodin 2 inhibited subunit dissociation and accelerated pointed-end elongation, reaching a plateau rate of 1.6 subunits s⁻¹ at actin monomer concentrations above 2 µM.
Immobilized leiomodin 2 processively elongated pointed ends at 1.3 subunits s⁻¹ with 2 µM actin monomers, dissociating stochastically with a half-time of ~ 8 min.
Cryo-EM structures resolved the leiomodin 2 leucine-rich repeat domain (residues 186–370) and D-loop binding site bound to pointed ends with and without an incoming actin subunit.

Structured PICO

P

Population

in vitro actin filaments and muscle cells

I

Intervention

leiomodin 2

C

Comparator

free pointed ends (without leiomodin 2)

O

Outcome

rate of elongation at pointed ends of actin filaments

Implication

Leiomodin 2 is the first identified molecule that promotes the elongation of actin filaments at their slow-growing pointed ends, revealing a novel mechanism in muscle cell biology.

Abstract

Biophysical and structural studies have found that leiomodin 2, a protein discovered in muscle cells, is the first example of a molecule that promotes the elongation of actin filaments at their slowly growing “pointed ends.” This breakthrough will stimulate work to answer many puzzling questions about the mechanism of this process.

Discussion

No takes yet. Share an insight, caveat, or question.

Cite This Study

Thomas D. Pollard (2026) reported an editorial. Leiomodin 2 vs. Free pointed ends (no leiomodin 2) was evaluated on Elongation rate at pointed ends of actin filaments. Leiomodin 2 promotes the elongation of actin filaments at their slowly growing pointed ends, plateauing at 1.6 subunits per second at actin monomer concentrations above 2 µM.

synapsesocial.com/papers/6a65a825d3aea3239cd78a4e https://doi.org/10.1038/s41467-026-75794-z

View Full Paper

Ask AI

Bookmark

Share

Leiomodin2 is a polymerase at the pointed ends of actin filaments

Figures

Key Points

Structured PICO

Implication

Abstract

Discussion

Cite This Study

Leiomodin2 is a polymerase at the pointed ends of actin filaments

Figures

Key Points

Structured PICO

Implication

Abstract

Discussion

Cite This Study

Keep reading

Keep reading