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DAP-12
TYRO protein tyrosine kinase-binding protein is an adapter protein that in humans is encoded by the ''TYROBP'' gene. Function This gene encodes a transmembrane signaling polypeptide which contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain. The encoded protein may associate with the killer cell immunoglobulin-like receptor (KIR) family of membrane glycoproteins and may act as an activating signal transduction element. This protein may bind zeta-chain associated protein kinase 70 kDa (ZAP-70) and spleen tyrosine kinase (SYK) and play a role in signal transduction, bone modeling, brain myelination, and inflammation. Mutations within this gene have been associated with polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), also known as Nasu-Hakola disease. Its putative receptor, triggering receptor expressed on myeloid cells 2 (TREM2), also causes PLOSL. Two alternative transcript variants encoding distin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Tyrosine Kinase
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions. Tyrosine kinases belong to a larger class of enzymes known as protein kinases which also attach phosphates to other amino acids such as serine and threonine. Phosphorylation of proteins by kinases is an important mechanism for communicating signals within a cell ( signal transduction) and regulating cellular activity, such as cell division. Protein kinases can become mutated, stuck in the "on" position, and cause unregulated growth of the cell, which is a necessary step for the development of cancer. Therefore, kinase inhibitors, such as imatinib and osimertinib, are often effective cancer treatments. Most tyrosine kinases have an associated protein tyrosine phosphatase, which removes the phosphate group. Reaction Protein kinases are a group of enzymes that possess a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoreceptor Tyrosine-based Activation Motif
An immunoreceptor tyrosine-based activation motif (ITAM) is a conserved sequence of four amino acids that is repeated twice in the cytoplasmic tails of non-catalytic tyrosine-phosphorylated receptors, cell-surface proteins found mainly on immune cells. Its major role is being an integral component for the initiation of a variety of signaling pathway and subsequently the activation of immune cells, although different functions have been described, for example an osteoclast maturation. Structure The motif contains a tyrosine separated from a leucine or isoleucine by any two other amino acids, giving the signature YxxL/I. Two of these signatures are typically separated by between 6 and 8 amino acids in the cytoplasmic tail of the molecule (YxxL/Ix(6-8)YxxL/I). However, it is worth noting that in various sources, this consensus sequence differs, mainly in the number of amino acids between individual signatures. Apart from ITAMs which have the structure described above, there is also a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Killer Cell Immunoglobulin-like Receptor
Killer-cell immunoglobulin-like receptors (KIRs), are a family of type I transmembrane glycoproteins expressed on the plasma membrane of natural killer (NK) cells and a minority of T cells. At least 15 genes and 2 pseudogenes encoding KIR map in a 150-kb region of the leukocyte receptor complex (LRC) on human chromosome 19q13.4. They regulate the killing function of these cells by interacting with major histocompatibility (MHC) class I molecules, which are expressed on all nucleated cell types. KIR receptors can distinguish between MHC I allelic variants, which allows them to detect virally infected cells or transformed cells. KIRs are paired receptors with both activating and inhibitory functions; most KIRs are inhibitory: their recognition of MHC molecules suppresses the cytotoxic activity of their NK cell. A limited number of KIRs are activating: their recognition of MHC molecules activates the cytotoxic activity of their cell. Initial expression of KIRs on NK cells i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Transduction
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway. When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events. At the molecular level, such responses include changes in the transcription or translation of genes, and post-translational and conformational changes in proteins, as well as changes in their location. These molecular events are the basic mechanisms controlling cell growth, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZAP-70
ZAP-70 (Zeta-chain-associated protein kinase 70) is a protein normally expressed near the surface membrane of lymphocytes (T cells, natural killer cells, and a subset of B cells). It is most prominently known to be recruited upon antigen binding to the T cell receptor (TCR), and it plays a critical role in T cell signaling. ZAP-70 was initially discovered in TCR-stimulated Jurkat cells, an immortal line of human T lymphocytes, in 1991. Its molecular weight is 70 kDa, and it is a member of the protein-tyrosine kinase family and is a close homolog of SYK. SYK and ZAP70 share a common evolutionary origin and split from a common ancestor in the jawed vertebrates. The importance of ZAP-70 in T cell activation was determined when comparing ZAP-70 expression in patients with SCID (severe combined immunodeficiency). ZAP-70 deficient individuals were found to have no functioning T cells in their peripheral blood, suggesting that ZAP-70 is a critical component of T cell activation and de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrosine-protein Kinase SYK
Tyrosine-protein kinase SYK, also known as spleen tyrosine kinase, is an enzyme which in humans is encoded by the ''SYK'' gene. Function SYK, along with ZAP70, is a member of the Syk family of tyrosine kinases. These cytoplasmic non-receptor tyrosine kinases share a characteristic dual SH2 domain separated by a linker domain. However, activation of SYK relies less on phosphorylation by Src family kinases than ZAP70. SYK and ZAP70 share a common evolutionary origin and split from a common ancestor in the jawed vertebrates. While Syk and ZAP70 are primarily expressed in hematopoietic tissues, a variety tissues express Syk. Within B and T cells, respectively, Syk and ZAP70 transmit signals from the B-cell receptor and T-cell receptor. Syk plays a similar role in transmitting signals from a variety of cell surface receptors including CD74, Fc receptor, and integrins. Function during development Mice that lack Syk completely (Syk−/−, Syk-knockout) die during embryonic deve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone Modeling
Bone remodeling (or bone metabolism) is a lifelong process where mature bone tissue is removed from the skeleton (a process called ''bone resorption'') and new bone tissue is formed (a process called ''ossification'' or ''new bone formation''). These processes also control the reshaping or replacement of bone following injuries like fractures but also micro-damage, which occurs during normal activity. Remodeling responds also to functional demands of the mechanical loading. In the first year of life, almost 100% of the skeleton is replaced. In adults, remodeling proceeds at about 10% per year. An imbalance in the regulation of bone remodeling's two sub-processes, bone resorption and bone formation, results in many metabolic bone diseases, such as osteoporosis. Physiology Bone homeostasis involves multiple but coordinated cellular and molecular events. Two main types of cells are responsible for bone metabolism: osteoblasts (which secrete new bone), and osteoclasts (which brea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myelination
Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However, unlike the plastic covering on an electrical wire, myelin does not form a single long sheath over the entire length of the axon. Rather, myelin sheaths the nerve in segments: in general, each axon is encased with multiple long myelinated sections with short gaps in between called nodes of Ranvier. Myelin is formed in the central nervous system (CNS; brain, spinal cord and optic nerve) by glial cells called oligodendrocytes and in the peripheral nervous system (PNS) by glial cells called Schwann cells. In the CNS, axons carry electrical signals from one nerve cell body to another. In the PNS, axons carry signals to muscles and glands or from sensor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and initiate tissue repair. The five cardinal signs are heat, pain, redness, swelling, and Functio laesa, loss of function (Latin ''calor'', ''dolor'', ''rubor'', ''tumor'', and ''functio laesa''). Inflammation is a generic response, and therefore it is considered as a mechanism of innate immune system, innate immunity, as compared to adaptive immune system, adaptive immunity, which is specific for each pathogen. Too little inflammation could lead to progressive tissue destruction by the harmful stimulus (e.g. b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycystic Lipomembranous Osteodysplasia With Sclerosing Leukoencephalopathy
Nasu–Hakola disease also known as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy is a rare disease characterised by early-onset dementia and multifocal bone cysts. It is caused by autosomal recessive loss of function mutations in either the ''TREM2'' or ''TYROBP'' gene that are found most frequently in the Finnish and Japanese populations. Signs and symptoms Four stages are recognised in this condition. The first (latent stage) show no symptoms or signs. This stage typically lasts up to the early 20s. This is followed by the osseous stage. This is characterised by recurrent bone pain usually affecting the long bones of the limbs. This is usually followed by pathological fractures of these bones. The third stage (early neurological) is marked by the onset of symptoms typical of a frontal lobe syndrome (euphoria, lack of concentration, loss of judgment and social inhibitions) with memory loss. Epilepsy may occur. This stage usually has its onset in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TREM2
Triggering receptor expressed on myeloid cells 2 (TREM2) is a protein that in humans is encoded by the ''TREM2'' gene. TREM2 is expressed on macrophages, immature monocyte-derived dendritic cells, osteoclasts, and microglia, which are immune cells in the central nervous system. In the liver, TREM2 is expressed by several cell types, including macrophages, that respond to injury. In the intestine, TREM2 is expressed by myeloid-derived dendritic cells and macrophage. TREM2 is overexpressed in many tumor types and has anti-inflammatory activities. It might therefore be a good therapeutic target. Gene The TREM2' gene lies on the sixth chromosome in humans, specifically in location 6p21.1. The gene has 5 coding exon regions. Alternative splicing of the ''TREM2'' mRNA transcript leads to different isoforms of the protein being produced upon translation. Specifically, ''TREM2'' mRNA has 3 different isoforms containing 3 consistent exons, and 2 that vary between the isoforms. ''TREM2'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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