| CALB2 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | CALB2 , CAB29, CAL2, CR, calbindin 2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 114051 MGI: 101914 HomoloGene: 1318 GeneCards: CALB2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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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. Symptoms usually become apparent in the first two months of life. Complications may include enterocolitis, megacolon, bowel obstruction and intestinal perforation.
Keratin 20, often abbreviated CK20, is a protein that in humans is encoded by the KRT20 gene.
Immunohistochemistry (IHC) is the most common application of immunostaining. It involves the process of selectively identifying antigens (proteins) in cells of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues. IHC takes its name from the roots "immuno", in reference to antibodies used in the procedure, and "histo", meaning tissue. Albert Coons conceptualized and first implemented the procedure in 1941.
Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4. In the mammalian retina, there are two additional categories of opsins, both involved in the formation of visual images: rhodopsin and photopsin in the rod and cone photoreceptor cells, respectively.
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 nuclei 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.
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 in the chick 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.
The EF hand is a helix–loop–helix structural domain or motif found in a large family of calcium-binding proteins.
Calcium-binding proteins are proteins that participate in calcium cell signalling 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.
p16, is a protein that slows cell division by slowing the progression of the cell cycle from the G1 phase to the S phase, thereby acting as a tumor suppressor. It is encoded by the CDKN2A gene. A deletion in this gene can result in insufficient or non-functional p16, accelerating the cell cycle and resulting in many types of cancer.
Parvalbumin (PV) is a calcium-binding protein with low molecular weight. In humans, it is encoded by the PVALB gene. It is not a member of the albumin family; it is named for its size and its ability to coagulate.
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.
Cannabinoid receptor type 1 (CB1), also known as cannabinoid receptor 1, is a G protein-coupled cannabinoid receptor that in humans is encoded by the CNR1 gene. The human CB1 receptor is expressed in the peripheral nervous system and central nervous system. It is activated by: endocannabinoids, a group of retrograde neurotransmitters that include anandamide and 2-arachidonoylglycerol (2-AG); plant phytocannabinoids, such as the compound THC which is an active ingredient of the psychoactive drug cannabis; and, synthetic analogs of THC. CB1 is antagonized by the phytocannabinoid tetrahydrocannabivarin (THCV).
Transcription factor SOX-10 is a protein that in humans is encoded by the SOX10 gene.
Inositol monophosphatase 1 is an enzyme that in humans is encoded by the IMPA1 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.
