Question

The mechanism by which some actin-binding proteins significantly increase the rate at which formation of an actin filament is initiated is:

a. By acting as actin severing proteins.
b. By stabilizing complexes of two or more monomers.
c. By sequestering actin monomers.
d. By acting as an ATP-exchange factor for the g-actin subunit.
e. By promoting hydrolysis of the ATP bound by the g-actin subunit.

Answer 1

Actin-binding proteins facilitate the formation of actin filaments by stabilizing complexes of actin monomers, which is essential for the dynamic cytoskeletal functions in cells.

Step-by-step explanation:

The mechanism by which some actin-binding proteins significantly increase the rate at which formation of an actin filament is initiated is by stabilizing complexes of two or more monomers. These proteins effectively nucleate the formation of actin filaments by lowering the energy barrier for adding actin monomers to a growing filament. As actin monomers bind ATP and join the plus end of the filament, the ATP is quickly hydrolyzed to ADP, which destabilizes the filament. Yet in living cells, certain actin-binding proteins can facilitate the assembly of actin monomers into a polymer by stabilizing these initial interactions. These actions are vital for the dynamic restructuring of the cytoskeleton, which is critical for cell motility, division, and maintaining cell shape.