Final answer:
The α-helical region of the rod interacts with another similar region to form a dimer in a 'coiled-coil' configuration, which is stabilized by hydrogen bonding and further assembles into higher order structures providing cell stability.
Step-by-step explanation:
The α-helical region of the rod interacts with the α-helical region of another monomer in a 'coiled-coil' configuration to form a dimer. This interaction and formation of a dimer is a common feature in the structure of intermediate filament proteins. Through a process known as dimerization, two monomers align their α-helical regions so that their hydrophobic faces come together, allowing their hydrophilic faces to interact with the aqueous environment. Each α-helix in the dimer structure is stabilized by hydrogen bonds, which occur every 3.6 residues along the peptide chain. These helices twist around each other, resembling a coiled rope, which contributes to the filament's strength and elasticity.
Dimers can further associate into tetramers and higher order structures, thereby forming the intermediate filament network within the cell. Notably, intermediate filaments do not possess polarity, unlike other cytoskeletal elements such as microtubules and actin filaments. This allows them to provide the cell with mechanical strength and the capacity to endure stretch, a property particularly important in cells that experience mechanical stress.