Final answer:
Verprolin and WASp regulate the actin cytoskeleton by promoting actin polymerization and interacting with the Arp2/3 complex, which nucleates new filaments. This process is crucial for cell movement, shape, and division. Substrate stiffness is an external factor that can influence the organization of the cytoskeleton.
Step-by-step explanation:
Verprolin and WASp (Wiskott-Aldrich syndrome protein) play critical roles in the regulation of the actin cytoskeleton. WASp is part of a family of proteins that promote actin polymerization, which is essential for various cellular functions including movement, division, and maintaining cell shape. Verprolin is linked with WASp and is known to be involved in actin filament elongation.
When activated, WASp interacts with the Arp2/3 complex, which serves as a nucleation core for the formation of new actin filaments. The energy for actin polymerization is provided by ATP. As new actin monomers add to the growing filament, they push outwards, creating forces that can move cellular components or change the cell's shape.
Microfilaments are composed of two intertwined strands of actin and work together with motor proteins like myosin to drive processes such as muscle contraction and cell motility. In cell division, actin filaments contribute to the formation of a cleavage furrow, leading to cytokinesis. The cytoskeleton's dynamics, including actin filament assembly and arrangement, can be affected by external factors like substrate stiffness, which influences myofibril assembly.