Actin Crosslinking Crosslinking of actin filaments is a critical step in cell motility and is a fundamental process in filopodia protrusion and lamellipodia formation. Smaller cross-linking proteins that are more globular (e.g. fascin) or have more than one actin binding site (e.g. fimbrin, [...]

Alpha-actinin α-actinin is an actin-binding protein [1] and component of the actin crosslinking functional modules; it lacks G-actin binding activity and lacks actin initiation/nucleation activity [2]. α-actinin is an important organizer of the cytoskeleton that belongs to the spectrin superfamily (which includes spectrin, dystrophin, [...]

Fascin Fascin is the major actin crosslinking protein found in a wide range of filopodia [1][2][3]. This protein has been shown to work in concert with other cross linkers such as α-actinin to produce filopodia, although fascin itself is sufficient to form filopodia-like bundles [...]

Filamin The filamin family of proteins bind to both actin and a number of signaling molecules including Rho GTPases. Evidence for this was shown with the loss of Filamin-A in M2 Melanoma cells, which prevented RalA- and Cdc42- mediated filopodia formation [1]. Filamin A [...]

Fimbrin Fimbrin (aka plastin homologue, accumentin) is an actin binding protein that was originally identified in microvilli [1][2]. This schematic diagram illustrates the molecular organization of fimbrin as depicted in this resource, and highlights the relevant domains for binding to actin filaments. [...]

I-BAR and Other Proteins/Factors Proteins containing I-BAR (inverted Bin/amphiphysin/Rvs i.e. IRSp53 Missing-in-metastasis homology Domain or IMD) cooperate with various components of actin filament assembly, to promote filopodia protrusion, via several mechanisms including the stimulation of F-actin crosslinking [1]. This schematic diagram illustrates the [...]

What is capping protein? Capping protein is involved in actin filament assembly and disassembly Capping proteins control access to the free barbed ends of actin filaments and is therefore a major factor affecting actin filament elongation. Capping proteins have a high affinity for barbed [...]

What are intermediate filaments? Intermediate filaments are a primary component of the cytoskeleton, although they are not found in all eukaryotes, and are absent in fungi and plants [1]. These filaments, which extend throughout the cytoplasm and inner nuclear membrane are composed from a [...]

How are intermediate filaments assembled? The soluble subunit for creating intermediate filaments is a tetramer. The tetramer is created from monomers in a stepwise fashion (as reviewed in [1]). First, two monomers associate via their central domains to form parallel helical coils around each [...]

What are microtubules? Microtubules are hollow cylinders [1] that are approximately 25nm in diameter [2] and vary in length from 200 nm to 25 μm. They are formed by the lateral association of between 12 and 17 protofilaments into a regular helical lattice [2],[3]. [...]

What is microtubule dynamic instability? In most cell types, thirteen protofilaments associate laterally to form a microtubule. In a few cases microtubules contain more or fewer protofilaments [1]. Numerous interactions between the subunits give microtubules their stiffness and resistance to bending forces. The lateral [...]

What is the role of microtubules in mechanotransduction? Microtubules exist in all cells, however their influence in the mechanotransduction of mechanical stimuli has been described at length in cardiac striated muscle [1]. Mechanical stimuli also affect microtubule formation and proliferation. This has been observed [...]