Intermediate Filaments

Intermediate filaments have an average diameter of about 10 nm and consist of several proteins that depend on the cell or tissue type. The proteins differ chemically and also in their cellular roles. 1. Keratins are a family of proteins found in most epithelial(a membranous cellular tissue that covers a free surface or lines a tube or cavity of an animal body and serves especially to enclose and protect the other parts of the body, to produce secretions and excretions, and to function in assimilation) cells. The variety of keratins speaks to the variety of functions carried out by skin, hair, and nails in protection from abrasion and dehydration. 2. Vinmentin filaments are found in cells of mesenchymal(loosely organized undifferentiated mostly mesodermal cells that give rise to such structures as connective tissues, blood, lymphatics, bone, and cartilage) origin such as fibroblasts(a connective-tissue cell of mesenchymal origin that secretes proteins and especially molecular collagen from which the extracellular fibrillar matrix of connective tissue forms), macrophages(functions in the protection of the body against infection and noxious substances), endothelial cells(thin flattened cells that lines internal body cavities), and chondroblasts. 3. Desmin is found in smooth muscle and also in the Z lines of skeletal and cardiac muscle. 4. Glial Fibrillary Acidic Protein is only found in glial cells (cells that deal with the supporting tissue intermingled with the essential elements of nervous tissue especially in the brain, spinal cord, and ganglia). 5. Neurofilaments are found in most neurons and are composed of at least three polypeptides. 6. Nuclear Laminins are found in the nuclear layer of cells.