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Updated: May 22, 2026

Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy
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Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy

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Preparation of filamentous actin for polarized total internal reflection fluorescence microscopy (polTIRFM) motility

John F Beausang, Yujie Sun, Margot E Quinlan

    Cold Spring Harbor Protocols
    |May 3, 2012
    PubMed

    Insights

    This study details methods for preparing filamentous actin (F-actin) for polarized total internal reflection fluorescence microscopy (polTIRFM). These techniques enable the analysis of single-molecule orientation and dynamics in actin-myosin interactions.

    Area of Science:

    • Biophysics
    • Molecular Biology
    • Microscopy

    Background:

    • Polarized total internal reflection fluorescence microscopy (polTIRFM) is a powerful technique for analyzing single-molecule orientation and dynamics.
    • Understanding the spatial orientation and rotational dynamics of macromolecules like filamentous actin (F-actin) is crucial in molecular motor studies.

    Purpose of the Study:

    • To provide a detailed protocol for preparing filamentous actin (F-actin) suitable for polarized total internal reflection fluorescence microscopy (polTIRFM) assays.
    • To enable the study of F-actin's interaction with myosin using advanced microscopy techniques.

    Main Methods:

    • Polymerization of unlabeled F-actin from monomeric actin (G-actin).
    • Sparse labeling of F-actin with 6'-iodoacetamidotetramethylrhodamine (6'-IATR).
    • Preparation of F-actin with a mix of unlabeled, biotinylated, and rhodamine-labeled monomers.

    Main Results:

    • Established procedures for generating various forms of F-actin for polTIRFM.
    • Demonstrated the adaptability of F-actin preparation for different labeling strategies.
    • Included a method for preparing rhodamine-phalloidin labeled actin.

    Conclusions:

    • The described protocols facilitate the use of F-actin in polTIRFM motility assays.
    • These methods allow for detailed investigation of F-actin's three-dimensional angular orientation and dynamics.
    • The prepared F-actin is suitable for studying actin-myosin interactions at the single-molecule level.

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