Vimentin is a protein which is encoded on human beings by the VIM gene, and takes its name from the Latin vimentum, which refers to a kind of array or mass of flexible rods. This gives some kind of hint as to its structure, as we will shortly see. Vimentin, importantly, is known as a type III intermediate filament (IF) protein, and it is primarily expressed in mesenchymal cells. The IF proteins more widely are found in all animal cells, along with bacteria, and all IF proteins are expressed in highly developmentally-regulated fashion. As such, vimentin is often used as a marker of mesenchymal-derived cells during both normal development and metastatic progression.
In a vimentin monomer, you find a central a-helical domain, as in all other intermediate filaments. This domain is capped on each end by amino head and carboxyl tail domains. Two monomers are usually likely to be co-translationally expressed, so that their formation of a coiled-coil dimer can happen, as this is the basic subunit of vimentin assembly.
Most importantly and significantly, vimentin plays a very central role in supporting and anchoring the position of the organelles in the cytosol. The cytosol is a kind of cytoplasmic matrix. Vimentin is usually either attached to the nucleus laterally or terminally, or the endoplasmic reticulum and mitochondria.
Importantly, vimentin provides cells with a resilience which is normally absent from the microtubule or actin filament networks, particularly when under mechanical stress in vivo. Because of this, it is believed that vimentin is the cytoskeletal component responsible for maintaining cell integrity.