The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including bacteria and archaea. It extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. In eukaryotes, it is composed of three main components, microfilaments, intermediate filaments and microtubules, and these are all capable of rapid growth or disassembly dependent on the cell's requirements.
Intermediate filaments (IFs) are cytoskeletal structural components found in the cells of vertebrates, and many invertebrates. Homologues of the IF protein have been noted in an invertebrate, the cephalochordate Branchiostoma.
Vimentin is a structural protein that in humans is encoded by the VIM gene. Its name comes from the Latin vimentum which refers to an array of flexible rods.
Peripherin is a type III intermediate filament protein expressed mainly in neurons of the peripheral nervous system. It is also found in neurons of the central nervous system that have projections toward peripheral structures, such as spinal motor neurons. Its size, structure, and sequence/location of protein motifs is similar to other type III intermediate filament proteins such as desmin, vimentin and glial fibrillary acidic protein. Like these proteins, peripherin can self-assemble to form homopolymeric filamentous networks, but it can also heteropolymerize with neurofilaments in several neuronal types. This protein in humans is encoded by the PRPH gene. Peripherin is thought to play a role in neurite elongation during development and axonal regeneration after injury, but its exact function is unknown. It is also associated with some of the major neuropathologies that characterize amyotropic lateral sclerosis (ALS), but despite extensive research into how neurofilaments and peripherin contribute to ALS, their role in this disease is still unidentified.
Glial fibrillary acidic protein (GFAP) is a protein that is encoded by the GFAP gene in humans. It is a type III intermediate filament (IF) protein that is expressed by numerous cell types of the central nervous system (CNS), including astrocytes and ependymal cells during development. GFAP has also been found to be expressed in glomeruli and peritubular fibroblasts taken from rat kidneys, Leydig cells of the testis in both hamsters and humans, human keratinocytes, human osteocytes and chondrocytes and stellate cells of the pancreas and liver in rats.
Keratin, type II cytoskeletal 8 also known as cytokeratin-8 (CK-8) or keratin-8 (K8) is a keratin protein that is encoded in humans by the KRT8 gene. It is often paired with keratin 18.
Synemin, also known as desmuslin, is a protein that in humans is encoded by the SYNM gene. Synemin is an intermediate filament (IF) family member. IF proteins are cytoskeletal proteins that confer resistance to mechanical stress and are encoded by a dispersed multigene family. This protein has been found to form a linkage between desmin, which is a subunit of the IF network, and the extracellular matrix, and provides an important structural support in muscle.
Gamma-crystallin D is a protein that in humans is encoded by the CRYGD gene.
Lens fiber major intrinsic protein is a protein that in humans is encoded by the MIP gene.
Beta-crystallin B2 is a protein that in humans is encoded by the CRYBB2 gene.
Crystallin, gamma C, also known as CRYGC, is a protein which in humans is encoded by the CRYGC gene.
Periplakin is a protein that in humans is encoded by the PPL gene.
Beta-crystallin B1 is a protein that in humans is encoded by the CRYBB1 gene. Variants in CRYBB1 are associated with autosomal dominant congenital cataract.
Gamma-crystallin B is a protein that in humans is encoded by the CRYGB gene.
Beta-crystallin A3 is a protein that in humans is encoded by the CRYBA1 gene.
Envoplakin is a protein that in humans is encoded by the EVPL gene.
Beta-crystallin A4 is a protein that in humans is encoded by the CRYBA4 gene.
BFSP2 is a gene that encodes the protein phakinin in humans.
Lens fiber membrane intrinsic protein is a protein that in humans is encoded by the LIM2 gene.
Lamin-B1 is a protein that in humans is encoded by the LMNB1 gene.
