Skip to content

Study · In vitro (cell-free) · 1993

5 results

Thymosin beta 10 and thymosin beta 4 are both actin monomer sequestering proteins.

Yu FX, Lin SC, Morrison-Bogorad M, Atkinson MA, Yin HL

The Journal of biological chemistry1 Jan 1993Cited by 141 (Europe PMC)

PMID8416954 (opens in a new tab)DOI10.1016/s0021-9258(18)54179-x (opens in a new tab)PepBankPUB-08416954
Publisher pagePubMedAsk about this study
Jump to 5 results

Summary

The beta-thymosins are a family of related peptides. Recently, thymosin beta 4 was identified as a significant actin monomer sequestering protein in cells. To determine if other beta-thymosins also bind actin, and how they may participate in the regulation of actin polymerization, we expressed thymosin beta 4 and its major homolog, thymosin beta 10, in bacteria and characterized their interactions with actin. Equilibrium sedimentation studies showed that thymosin beta 4 behaved as a monomeric protein in solution. Both beta-thymosins bound skeletal muscle actin and inhibited actin polymerization with similar Kd values (between 0.7-1 microM). They were not inhibited by polyphosphoinositides. Kinetic measurements showed that at high ratios of beta-thymosin to actin, beta-thymosin decreased the rate of barbed end filament growth. However, in spite of a close agreement between the kinetic and steady state Kd values, the rate of barbed end filament growth was slightly, but reproducibly, larger than expected, and this deviation was particularly noticeable at lower ratios of beta-thymosin to actin. We conclude that unlike profilin, beta-thymosins are primarily actin monomer sequestering proteins, although some aspects of their interactions with actin are still not completely understood.
CC BYText from Europe PMC. Highlighted sentences are the source of results.

Results from this study5

5 results from studies that gave the peptide. No result from this study comes from people.

  1. 01LabIn vitro (cell-free)Activity measurement

    In a cell-free assay, thymosin beta‑4 bound skeletal muscle actin and inhibited actin polymerization with a Kd between 0.7-1 microM.

    In plain wordsIn lab tests, thymosin beta‑4 bound muscle actin and stopped actin from forming filaments.

    Peptide
    Thymosin beta-4 (human)
    Outcome
    DecreaseBinding to skeletal muscle actin and inhibition of actin polymerization (Kd)
    Study

    n: not reported in source

    Purified skeletal muscle actin with recombinant thymosin beta 4
    Outcome group
    Receptor activity and mechanism · Pharmacology
    Studied dose
    Dose not stated

    Measurements

    Kd
    0.7 to 1 microM
    thymosin beta 4 with skeletal muscle actin

    Source sentences

    Summary
    Both beta-thymosins bound skeletal muscle actin and inhibited actin polymerization with similar Kd values (between 0.7-1 microM).
  2. 02LabIn vitro (cell-free)Other

    In equilibrium sedimentation studies, thymosin beta‑4 behaved as a monomeric protein in solution.

    In plain wordsIn lab tests, thymosin beta‑4 stayed as a single unit in solution.

    Peptide
    Thymosin beta-4 (human)
    Outcome
    Not applicableOligomeric state in solution
    Study

    n: not reported in source

    Purified skeletal muscle actin with recombinant thymosin beta 4
    Outcome group
    Receptor activity and mechanism · Pharmacology
    Studied dose
    Dose not stated

    Source sentences

    Summary
    Equilibrium sedimentation studies showed that thymosin beta 4 behaved as a monomeric protein in solution.
  3. 03LabIn vitro (cell-free)Activity measurement

    In a cell-free assay, thymosin beta‑4 and thymosin beta 10 were not inhibited by polyphosphoinositides.

    In plain wordsIn lab tests, polyphosphoinositides did not inhibit thymosin beta‑4.

    Peptide
    Thymosin beta-4 (human)
    Outcome
    No significant changeInhibition by polyphosphoinositides
    Study

    n: not reported in source

    Purified skeletal muscle actin with recombinant thymosin beta 4
    Outcome group
    Receptor activity and mechanism · Pharmacology
    Studied dose
    Dose not stated

    Source sentences

    Summary
    They were not inhibited by polyphosphoinositides.
    1 context sentence
    Summary · context
    Both beta-thymosins bound skeletal muscle actin and inhibited actin polymerization with similar Kd values (between 0.7-1 microM).
  4. 04LabIn vitro (cell-free)Activity measurement

    In kinetic measurements, at high ratios of thymosin beta‑4 to actin the rate of barbed end filament growth decreased.

    In plain wordsIn lab tests, high amounts of thymosin beta‑4 slowed the growth of actin filaments.

    Peptide
    Thymosin beta-4 (human)
    Outcome
    DecreaseRate of barbed end filament growth at high beta-thymosin to actin ratios
    Study

    n: not reported in source

    Purified skeletal muscle actin with recombinant thymosin beta 4
    Outcome group
    Receptor activity and mechanism · Pharmacology
    Studied dose
    Dose not stated

    Source sentences

    Summary
    Kinetic measurements showed that at high ratios of beta-thymosin to actin, beta-thymosin decreased the rate of barbed end filament growth.
  5. 05LabIn vitro (cell-free)Activity measurement

    In kinetic measurements, the rate of barbed end filament growth was slightly but reproducibly larger than expected from the Kd values, mainly at lower beta-thymosin to actin ratios.

    In plain wordsIn lab tests, actin filaments grew slightly faster than expected from binding values, mainly at lower amounts of thymosin beta‑4.

    Peptide
    Thymosin beta-4 (human)
    Outcome
    IncreaseBarbed end growth rate versus rate expected from Kd
    Study

    n: not reported in source

    Purified skeletal muscle actin with recombinant thymosin beta 4
    Outcome group
    Receptor activity and mechanism · Pharmacology
    Studied dose
    Dose not stated

    Source sentences

    Summary
    However, in spite of a close agreement between the kinetic and steady state Kd values, the rate of barbed end filament growth was slightly, but reproducibly, larger than expected, and this deviation was particularly noticeable at lower ratios of beta-thymosin to actin.

AI wrote and checked these results. AI can make mistakes, so check important results against the source.

Version history

PepBank keeps every version of the data on this study. Status changes from Retraction Watch, Europe PMC and Crossref are listed with their source.

  1. Version 2Current

    13 Oct 2026, 01:52 UTC

    Study results updated

  2. Version 1

    12 Oct 2026, 18:17 UTC

    First added · source update from Europe PMC

Subjects

Terms as the source lists them.

PepBank is a research reference. Talk to a doctor before you use any peptide.