Diversity of intermediate filament structure. Evidence that the alignment of coiled-coil molecules in vimentin is different from that in keratin intermediate filaments.

摘要: Although vimentin intermediate filaments (IF) are morphologically similar to all other IF types, cells have evolved different ways of manipulating and keratin IF. The structural basis for such differences is unknown. We explored this by use cross-linking experiments on oligomers, polymers, intact determine the axial length molecules degrees which neighboring aligned in Our data reveal that homodimer molecule (43.9 nm) clearly shorter than a heterodimer (46.2 nm). Vimentin assemblies contain three modes antiparallel molecular alignments: A11 A22 two-molecule or larger oligomeric assemblies, two staggered so as bring their 1B 2B rod domain segments, respectively, into register; A12 higher order largely overlapped. Since repeat (42.6 less length, means there an overlap (designated alignment ACN) about 1 nm (5-10 residues) between end beginning 1A segments similarly directed Interestingly, these four nearest neighbor alignments also occur However, degree stagger (staggers -19.5 versus -16.6 keratin, 23.3 28.6 nm, respectively). Two-dimensional surface lattice maps types very similar, except repeats 21.4 22.6 vimentin-keratin hybrid can be induced form vitro, they do not assemble structures. suggest incapable assembly vitro vivo simply because lengths exact different.