Recombinant Human Vimentin Protein, CF

The Vimentin protein is a 57 kDa class III intermediate filament (IF) protein that belongs to the intermediate filament family. Vimentin is the predominant intermediate filament in cells of mesenchymal origin such as vascular endothelium and blood cells (1-3). The human Vimentin cDNA encodes a 466 amino acid (aa) Vimentin protein that contains head and tail regions with multiple regulatory Ser/Thr phosphorylation sites, and a central rod domain with three coiled-coil regions separated by linkers (1, 2). The human Vimentin protein shares 97-98% aa identity with the mouse, rat, bovine and canine Vimentin proteins. Sixteen Vimentin coiled-coil dimers self-assemble to form intermediate (10-12 nm wide) filaments (4). These filaments then anneal longitudinally to form non-polarized fibers that support cell structure and withstand stress (4). Intermediate filament fibers are highly dynamic, and their half-life depends on the balance between kinase and phosphatase activity. For example, phosphorylation followed by dephosphorylation drives intermediate filament disintegration, followed by reorganization during mitosis (1, 5, 6). Interactions of head and tail domains link intermediate filaments with other structures such as actin and microtubule cytoskeletons (7). The Vimentin protein is involved in positioning autophagosomes, lysosomes and the Golgi complex within the cell (8). It facilitates cell migration and motility by recycling internalized trailing edge integrins back to the cell surface at the leading edge (9-11). Vimentin also helps maintain the lipid composition of cellular membranes, and caspase cleavage of the Vimentin protein is a key event in apoptosis (8, 12). Phosphorylation of the Vimentin protein promotes its secretion by TNF-alpha -stimulated macrophages (13). Extracellular Vimentin has been shown to associate with several microbes, and appears to promote an antimicrobial oxidative burst (13, 14). Cell-associated Vimentin can also interact with NKp46 to recruit NK cells to tuberculosis-infected monocytes (15).