Final answer:
Gelsolin, a calcium-regulated regulatory protein, binds to the plus end of actin filaments, influencing the cytoskeletal dynamics by capping and severing the filaments.
Step-by-step explanation:
The regulatory protein gelsolin is known to be calcium-regulated and plays a role in the dynamic rearrangement of actin filaments within the cytoskeleton. Actin filaments are polar structures with distinct plus (+) and minus (-) ends; they exhibit polarized polymerization and depolymerization dynamics. Gelsolin specifically binds to the plus end of actin filaments in the presence of calcium ions. This binding results in the severing of actin filaments and the capping of the plus end, which can lead to the regulation of filament length and the reorganization of the actin cytoskeleton. Additionally, actin polymerization is an energy-consuming, non-equilibrium process that is catalyzed by the binding of ATP to monomeric actin (G-actin), and it involves proteins like gelsolin to regulate its dynamics.