Actin Polymerization
Actin Polymerization - Related Videos
12:15
In Vitro Polymerization of F-actin on Early Endosomes
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Cited by 3 •
2017
Early endosome functions depend on F-actin polymerization. Here, we describe a microscopy-based in vitro assay that reconstitutes the nucleation and polymerization of F-actin on early endosomal membranes in test tubes, thus rendering this complex series of reactions amenable to biochemical and genetic manipulations.
01:42
Actin Polymerization
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2023
Actin polymerization occurs through the head-to-tail association of binding sites on monomeric actin or G-actin to form filamentous or F-actin. The polymerization can be divided into three phases ̶ nucleation, elongation, and steady-state phase. The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin...
01:13
Actin Polymerization and Cell Motility
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2023
Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells. Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
09:22
High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization
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Cited by 8 •
2014
Here we present a protocol to quantify phagocytosis of fluorescent particles by adherent macrophage cell line using a fluorometric method. This method facilitates a high throughput quantification of particle internalization as well as the resulting actin polymerization.
06:17
Measuring Protein Binding to F-actin by Co-sedimentation
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Cited by 18 •
2017
This protocol describes a method to test the ability of a protein to co-sediment with filamentous actin (F-actin) and, if binding is observed, to measure the affinity of the interaction.
FAQs
Actin polymerization proceeds through kinetically distinct stages. Nucleation creates a stable oligomer from ATP-bound monomers, providing the starting structure for filament growth. Elongation then adds subunits rapidly, whereas later ATP hydrolysis and subunit loss contribute to turnover. Separating these stages helps explain why filament assembly and disassembly can be coordinated within a cell.
ATP hydrolysis links filament assembly to remodeling rather than allowing actin structures to remain permanently stable. After ATP-bound actin supports filament formation, hydrolysis and subsequent subunit loss contribute to turnover. This relationship helps cells continually adjust their cytoskeletal organization, allowing actin-based structures to respond as cellular shape, movement, or mechanical conditions change.
Treadmilling reflects directional actin turnover involving the filament’s barbed and pointed ends. Subunit addition and loss can therefore occur as part of a continuing cycle rather than as a single static event. This dynamic behavior gives cells a way to remodel filament organization while preserving a responsive cytoskeletal framework for movement, shape changes, and structural support.
A useful analysis follows the process from ATP-bound monomers through nucleation, rapid elongation, ATP hydrolysis, and subunit loss. Examining these linked stages clarifies how stable oligomers initiate growth and how later turnover reshapes filaments. This framework helps interpret actin behavior as a regulated cycle of assembly and disassembly rather than an isolated construction event.
Actin polymerization contributes to several essential cellular activities, including cell migration, cytokinesis, membrane trafficking, and changes in cell shape. In each context, regulated filament remodeling helps reorganize the cytoskeleton in response to cellular demands. Studying these connections shows how molecular-scale actin dynamics support broader biological processes involving movement, division, transport, and architecture.
Actin polymerization provides a common framework for studying how cells organize internal architecture and respond mechanically to their environment. These properties make it relevant to developmental biology, infection research, and disease research, where altered cell movement, shape, trafficking, or structural organization may be important. Investigating actin dynamics therefore connects cytoskeletal mechanisms with wider biological outcomes.