What are Contractile Fibers? Certain myosin isoforms (i.e. myosin II) form bipolar assemblies via the extended coiled-coil domains in the heavy chains (see also “thick filaments”). Actin “thin filaments” with opposite polarity associate with thick filaments to create contractile bundles that can be found [...]
What is Actomyosin? Actomyosin refers to the actin-myosin complex that forms within the cytoskeleton. Actomyosin is inherently contractile, with the myosin motor protein able to pull on actin filaments. This property gives rise to contractile fibers that form the basis of skeletal muscle, and [...]
How does the contractome protein network regulate actomyosin contractility? Non-muscle myosin II isoforms have a similar structure and function to their muscle equivalents. However, their interaction with actin serves to generate cellular forces rather than muscular contraction. During non-muscle actomyosin contractility, non-muscle myosin II [...]
What are Blebs? Blebs are blister-like protrusions that occur at the cell surface (reviewed in [1]). Blebs form, and function, in a series of defined steps. They typically grow to a length of around 2 µm within 30 seconds, before shrinking back for another [...]
How does the tubulin complex assemble? Microtubules are made up of repeating units of α/β- tubulin heterodimers, which are assembled on a γ-tubulin ring complex (a complex of γ-tubulin and other protein components), during the nucleation phase. Tubulin Tubulin is a small globular protein [...]
How is microtubule assembly/disassembly regulated? GTP hydrolysis has been shown to be a key regulator of microtubule polymerization dynamics. Although the exact mechanisms are poorly understood, two opposing models have been proposed to describe how GTP could alter the conformation of α-tubulin/β-tubulin from the [...]
How do filopodia pull on a substrate? Although a reterograde motion of actin filaments is intrinsic in the formation of filopodia, the forces generated by actin treadmilling are too weak to facilitate the “pulling” mechanism required for rigidity sensing and other mechanosensing processes. This [...]
What causes filopodia retraction and collapse? Binding of filopodia to certain ligands or substratum may hinder filament assembly, thereby leading to changes that promote retraction, collapse or growth cone turning [1][2]. For example, substrate contacts with a repulsive signal on one side of a [...]
What are lamellipodia and lamella? The lamellipodia and lamella are plate-like extensions of the cell that play crucial roles in both cell motility and migration, and mechanosensing. These structures form and function over distinct steps. Lamellipodia are thin, sheet-like membrane protrusions found at the [...]
How do blebs expand? Expansion lasts between 5 to 30 seconds, following bleb initiation and preceding reformation of the cortical actomyosin cytoskeleton just beneath the membrane [1]. During this time, the bleb proceeds to grow as a result of actomyosin driven pressure, resulting in [...]
What are filopodia? Filopodia (singular filopodium) are thin membrane protrusions that act as antennae for a cell to probe the surrounding environment [1][2][3]. Nonprotruding filopodia are mechanistically related to microspikes [4]. Filopodia are commonly found embedded within, or protruding from the lamelliopodium at the [...]
What is the first step in filopodium formation? Actin nucleation initiates filopodium formation The first step in the formation of a filopodium is the nucleation of actin filaments from G-actin monomers. This is facilitated by various proteins known as nucleators, and may occur via [...]
A leading global university centred in Asia, NUS is Singapore's flagship university, offering a global approach to education and research with a focus on Asian perspectives and expertise.
One of four Research Centres of Excellence at NUS, MBI is working to identify, measure and describe how the forces for motility and morphogenesis are expressed at the molecular, cellular and tissue level.