| CALB2 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | CALB2 , CAB29, CAL2, CR, calbindin 2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 114051; MGI: 101914; HomoloGene: 1318; GeneCards: CALB2; OMA:CALB2 - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
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| Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Calretinin, also known as calbindin 2 (formerly 29 kDa calbindin), is a calcium-binding protein involved in calcium signaling. [5] In humans, the calretinin protein is encoded by the CALB2 gene. [6] [7]
This gene encodes an intracellular calcium-binding protein belonging to the troponin C superfamily. Members of this protein family have six EF-hand domains which bind calcium. This protein plays a role in diverse cellular functions, including message targeting and intracellular calcium buffering. [6]
Calretinin is abundantly expressed in neurons including retina (which gave it the name) [5] and cortical interneurons. [8] Expression was found in different neurons than that of the similar vitamin D-dependent calcium-binding protein, calbindin-28kDa. [5]
Calretinin has an important role as a modulator of neuronal excitability including the induction of long-term potentiation. [9] Loss of expression of calretinin in hippocampal interneurons has been suggested to be relevant in temporal lobe epilepsy. [10]
It is expressed in a number of other locations including hair follicles. [11]
Calretinin is a diagnostic marker for some human diseases, including Hirschsprung disease and some cancers.
Using immunohistochemistry, calretinin can be demonstrated in both benign mesothelium and in malignant mesothelioma [12] [13] and can be used to help differentiate different lung tumours. [14] Antibodies to calretinin can also be used to distinguish between different types of brain tumour, demonstrating only those with neuronal rather than glial, differentiation. [15] Furthermore, the essential function of calretinin in mesothelioma cell lines has been demonstrated in vitro and may be an interesting target for therapeutical approaches. [16]
In Hirschsprung disease, calretinin immunohistochemistry offers additional diagnostic value in specimens with inadequate amount of submucosa and rarely seen ganglion cells. The presence of ganglion cells consistently correlated with calretinin-positive thin nerve fibrils in the lamina propria, muscularis mucosae and superficial submucosa. These calretinin-positive thin neurofibrils are absent in the aganglionic segments of bowel and in the areas without ganglion cells from the junction of normal with diseased rectum. Calretinin is strongly expressed in the submucosal and subserosal nerve trunks in the ganglionic segment. No calretinin expression is seen in the nerve trunks in the rest of the aganglionic segment. It has faint expression in the thick nerve trunks from the areas without ganglion cells. Faint positivity of the thick submucosal and subserosal nerves in the absence of ganglion cells and calretinin positive nerve fibrils, is characteristic of the junction of the aganglionic-to-normal rectum. [17]
Hirschsprung's disease is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Most children develop signs and symptoms shortly after birth. However, others may be diagnosed later in infancy or early childhood. About half of all children with Hirschsprung's disease are diagnosed in the first year of life. Complications may include enterocolitis, megacolon, bowel obstruction and intestinal perforation.
The myenteric plexus provides motor innervation to both layers of the muscular layer of the gut, having both parasympathetic and sympathetic input, whereas the submucous plexus provides secretomotor innervation to the mucosa nearest the lumen of the gut.
Immunohistochemistry is a form of immunostaining. It involves the process of selectively identifying antigens (proteins) in cells and tissue, by exploiting the principle of antibodies binding specifically to antigens in biological tissues. Albert Hewett Coons, Ernest Berliner, Norman Jones and Hugh J Creech was the first to develop immunofluorescence in 1941. This led to the later development of immunohistochemistry.
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.
The matrix-core theory of thalamus, first proposed by Ted Jones, states that neurons in the thalamus belong to either a calbindin-immunopositive matrix of diffusely and widely projecting neurons, or to a parvalbumin-immunopositive core of precisely projecting neurons. Unfortunately only one nucleus is simply immunoreactive to just one of three calcium binding proteins, and that is the centromedial nuclei which stains for parvalbumin. A given region usually stains for two of the three proteins—parvalbumin, calbindin, and calretinin The neurons comprising the core are believed to be involved in propagation of 'driving' information, whereas neurons comprising the matrix are believed to play a more modulatory role.
Canalicular adenoma is a type of growth that occurs in human salivary glands. It is a benign growth which occurs in the epithelial cells, and is typically arranged in columns of cells that form interconnecting cords. Canalicular adenoma is a very rare benign neoplasm; it constitutes about 1% of all salivary gland tumors and about 4% of all benign salivary gland tumors.
Calbindins are three different calcium-binding proteins: calbindin, calretinin and S100G. They were originally described as vitamin D-dependent calcium-binding proteins in the intestine and kidney of chicks and mammals. They are now classified in different subfamilies as they differ in the number of Ca2+ binding EF hands.
Oncomodulin is a parvalbumin-family calcium-binding protein expressed and secreted by macrophages.
Complement receptor type 2 (CR2), also known as complement C3d receptor, Epstein-Barr virus receptor, and CD21, is a protein that in humans is encoded by the CR2 gene.
Calcium-binding proteins are proteins that participate in calcium cell signaling pathways by binding to Ca2+, the calcium ion that plays an important role in many cellular processes. Calcium-binding proteins have specific domains that bind to calcium and are known to be heterogeneous.
Neurogranin is a calmodulin-binding protein expressed primarily in the brain, particularly in dendritic spines, and participating in the protein kinase C signaling pathway. Neurogranin has recently been found in aortic endothelial cells and cardiomyocytes. Neurogranin is the main postsynaptic protein regulating the availability of calmodulin, binding to it in the absence of calcium. Phosphorylation by protein kinase C lowers its binding ability. NRGN gene expression is controlled by thyroid hormones. Human neurogranin consists of 78 amino acids.
Parvalbumin (PV) is a calcium-binding protein with low molecular weight. In humans, it is encoded by the PVALB gene. It is a member of the albumin family; it is named for its size and its ability to coagulate.
A nerve tissue protein is a biological molecule related to the function and maintenance of normal nervous tissue. An example would include, for example, the generation of myelin which insulates and protects nerves. These are typically calcium-binding proteins.
Tumor protein p63, typically referred to as p63, also known as transformation-related protein 63 is a protein that in humans is encoded by the TP63 gene.
Zinc finger E-box-binding homeobox 2 is a protein that in humans is encoded by the ZEB2 gene. The ZEB2 protein is a transcription factor that plays a role in the transforming growth factor β (TGFβ) signaling pathways that are essential during early fetal development.
Transcription factor SOX-10 is a protein that in humans is encoded by the SOX10 gene.
S100 calcium-binding protein G (S100G) is a protein that in humans is encoded by the S100G gene.
Secretagogin is a protein that in humans is encoded by the SCGN gene.
A neuronal lineage marker is an endogenous tag that is expressed in different cells along neurogenesis and differentiated cells such as neurons. It allows detection and identification of cells by using different techniques. A neuronal lineage marker can be either DNA, mRNA or RNA expressed in a cell of interest. It can also be a protein tag, as a partial protein, a protein or an epitope that discriminates between different cell types or different states of a common cell. An ideal marker is specific to a given cell type in normal conditions and/or during injury. Cell markers are very valuable tools for examining the function of cells in normal conditions as well as during disease. The discovery of various proteins specific to certain cells led to the production of cell-type-specific antibodies that have been used to identify cells.
Calbindin 1 is a protein that in humans is encoded by the CALB1 gene. It belongs to the calbindin family of calcium-binding proteins, along with calretinin (CALB2).
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
