Final answer:
In the cell, intermediate filament disassembly is triggered by subunit phosphorylation, a process involving the addition of a phosphate group which can lead to structural changes in the intermediate filament subunits.
Step-by-step explanation:
In the cell, intermediate filament disassembly is triggered by subunit phosphorylation. Intermediate filaments are made up of fibrous subunits of a protein called keratin. They play a critical role in maintaining cell shape and structure, resisting tension, and anchoring organelles as well as forming special cell-to-cell junctions.
Phosphorylation of these subunits can lead to changes in the filament stability, thus allowing the intermediate filaments to disassemble when needed. This mechanism of action contrasts with the ATP hydrolysis involved in microtubule dynamics. While the presence of Ca²⁺ ions and ATP hydrolysis can affect other components of the cytoskeleton, such as microfilaments and microtubules, they are not responsible for the disassembly of intermediate filaments.