Conserved segments 1A and 2B of the intermediate filament dimer: their atomic structures and role in filament assembly.

Intermediate filaments (IFs) are key components of the cytoskeleton in higher eukaryotic cells. The elementary IF 'building block' is an elongated coiled-coil dimer consisting of four consecutive alpha-helical segments. The segments 1A and 2B include highly conserved sequences and are critically involved in IF assembly.