12 Questions
What are the functions of actin binding proteins, such as cofilin and gelsolin, in cell locomotion?
They may create additional free barbed ends for growth or act as capping proteins.
What is the role of cross-linking and bundling proteins in cell locomotion?
They form a mesh-like network for support or parallel groupings, as seen in microvilli.
What is the function of membrane-binding proteins in cell locomotion?
They provide anchorage for changes in membrane shape.
What is the role of the Arp 2/3 complex in directed motility?
It activates filament nucleating proteins in response to stimuli, leading to the polymerization of actin-ATP.
What is the role of cofilin in the depolymerization of actin filaments during directed motility?
It mediates the depolymerization of the (-) ends of capped microfilaments, releasing ADP to allow for the formation of actin-ATP.
What is the role of vinculin staining at focal adhesions in cell locomotion?
It allows for the formation of focal adhesions between the leading edge of the lamellipodium and the substratum, enabling the bulk of the cell to be moved forward by myosin and actin.
What is the difference in the critical concentration of ATP-actin required for addition to the "barbed" and "pointed" ends of a microfilament?
The critical concentration of ATP-actin required for addition to the (+) end is lower than that for the (-) end.
What is the role of the Arp 2/3 complex in actin filament formation?
The Arp 2/3 complex serves as a template for the addition of actin monomers to add branches to the filament.
What is the function of monomer-sequestering proteins, such as thymosins, in regulating actin filament dynamics?
Monomer-sequestering proteins bind to actin-ATP monomers, preventing polymerization and regulating the rate of polymerization and depolymerization.
What is the role of end-blocking (capping) proteins in regulating actin filament dynamics?
End-blocking proteins prevent the addition or loss of actin monomers at the (+) or (-) end of the filament.
What is the function of depolymerizing proteins, such as cofilin, in regulating actin filament dynamics?
Depolymerizing proteins bind to the pointed end of the filament, causing depolymerization.
Where are actin networks typically located in the cell, and what is their role in cellular motility?
Actin networks are typically located in the cell cortex, below the cell membrane, and are essential for cellular motility, including processes such as endocytosis, phagocytosis, and cytokinesis.
Test your understanding of actin and cell motility, including microfilaments, their assembly, and disassembly. Learn about the role of ATP/ADP and the critical concentration for adding ATP-actin to either end. Based on Karp's Cell & Molecular Biology (2020) Fig 9.39.
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