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B7 (protein)
B7 is a type of integral membrane protein found on activated antigen-presenting cells (APC) that, when paired with either a CD28 or CD152 (CTLA-4) surface protein on a T cell, can produce a costimulatory signal or a coinhibitory signal to enhance or decrease the activity of a major histocompatibility complex, MHC-T cell receptor, TCR signal between the APC and the T cell, respectively. Binding of the B7 of APC to CTLA-4 of T-cells causes inhibition of the activity of T-cells. There are two major types of B7 proteins: B7-1 or CD80, and B7-2 or CD86. It is not known if they differ significantly from each other. So far CD80 is found on dendritic cells, macrophages, and activated B cells, CD86 (B7-2) on B cells. The proteins CD28 and CTLA-4 (CD152) each interact with both B7-1 and B7-2. Costimulation There are several steps to activation of the immune system against a pathogen. The T-cell receptor must first interact with the Major histocompatibility complex (MHC) surface protein. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integral Membrane Protein
An integral, or intrinsic, membrane protein (IMP) is a type of membrane protein that is permanently attached to the biological membrane. All ''transmembrane proteins'' are IMPs, but not all IMPs are transmembrane proteins. IMPs comprise a significant fraction of the proteins encoded in an organism's genome. Proteins that cross the membrane are surrounded by annular lipids, which are defined as lipids that are in direct contact with a membrane protein. Such proteins can only be separated from the membranes by using detergents, nonpolar solvents, or sometimes denaturing agents. Structure Three-dimensional structures of ~160 different integral membrane proteins have been determined at atomic resolution by X-ray crystallography or nuclear magnetic resonance spectroscopy. They are challenging subjects for study owing to the difficulties associated with extraction and crystallization. In addition, structures of many water-soluble protein domains of IMPs are available in the Prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anergy
In immunology, anergy is a lack of reaction by the body's defense mechanisms to foreign substances, and consists of a direct induction of peripheral lymphocyte tolerance. An individual in a state of anergy often indicates that the immune system is unable to mount a normal immune response against a specific antigen, usually a self-antigen. Lymphocytes are said to be ''anergic'' when they fail to respond to their specific antigen. Anergy is one of three processes that induce tolerance, modifying the immune system to prevent self-destruction (the others being clonal deletion and immunoregulation). Mechanism This phenomenon was first described in B lymphocytes by Gustav Nossal and termed "clonal anergy." The clones of B lymphocytes in this case can still be found alive in the circulation, but are ineffective at mounting immune responses. Later Ronald Schwartz and Marc Jenkins described a similar process operating in the T lymphocyte. Many viruses (HIV being the most extreme examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD278
Inducible T-cell costimulator is an immune checkpoint protein that in humans is encoded by the ''ICOS'' gene. CD278 or ICOS (Inducible T-cell COStimulator) is a CD28-superfamily costimulatory molecule that is expressed on activated T cells. It is thought to be important for Th2 cells in particular. Function The protein encoded by this gene belongs to the CD28 and CTLA-4 cell-surface receptor family. It forms homodimers and plays an important role in cell-cell signaling, immune responses and regulation of cell proliferation. Knockout phenotype Compared to wild-type naïve T cells, ICOS-/- T cells activated with plate-bound anti- CD3 have reduced proliferation and IL-2 secretion. The defect in proliferation can be rescued by addition of IL-2 to the culture, suggesting the proliferative defect is due either to ICOS-mediated IL-2 secretion or the activation of similar signaling pathways between ICOS and IL-2. In terms of Th1 and Th2 cytokine secretion, ICOS-/- CD4+ T cell a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ICOSLG
ICOS ligand (ICOSLG, ICOSL or GL50) is a protein that in humans is encoded by the ''ICOSLG'' gene located at chromosome 21. ICOSLG has also been designated as CD275 (cluster of differentiation 275). ICOSLG is glycosylated transmembrane structure, which is classified as a member of the B7 (protein), B7 family due to the significant homology with B7 family members. The B7/CD28 superfamily provides both positive and negative co-signals to immunocytes in immune responses. The interaction of ICOSLG with CD278, ICOS, the specific receptor for ICOSLG, is critically involved in the activation, proliferation, differentiation and cytokine production of T cells as well as in the antibody secretion from B cells during secondary immune responses. ICOSLG, which is extensively expressed in both non-lymphatic and lymphatic tissues, is an important molecule in upregulating and promoting T cell immune responses. Expression of ICOSLG in naive B cells and monocytes in PBMCs is at a low level. After ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PD-1
Programmed cell death protein 1, also known as PD-1 and CD279 (cluster of differentiation 279), is a protein on the surface of T and B cells that has a role in regulating the immune system's response to the cells of the human body by down-regulating the immune system and promoting self-tolerance by suppressing T cell inflammatory activity. This prevents autoimmune diseases, but it can also prevent the immune system from killing cancer cells. PD-1 is an immune checkpoint and guards against autoimmunity through two mechanisms. First, it promotes apoptosis (programmed cell death) of antigen-specific T-cells in lymph nodes. Second, it reduces apoptosis in regulatory T cells (anti-inflammatory, suppressive T cells). PD-1 inhibitors, a new class of drugs that block PD-1, activate the immune system to attack tumors and are used to treat certain types of cancer. The PD-1 protein in humans is encoded by the ''PDCD1'' gene. PD-1 is a cell surface receptor that belongs to the immunoglobu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDCD1LG2
Programmed cell death 1 ligand 2 (also known as PD-L2, B7-DC) is a protein that in humans is encoded by the ''PDCD1LG2'' gene. PDCD1LG2 has also been designated as CD273 (cluster of differentiation 273). PDCD1LG2 is an immune checkpoint receptor ligand which plays a role in negative regulation of the adaptive immune response. PD-L2 is one of two known ligands for Programmed cell death protein 1 (PD-1). Structure PD-L2 is a cell surface receptor belonging to the B7 protein family. It consists of both an immunoglobulin-like variable domain and an immunoglobulin-like constant domain in the extracellular region, a transmembrane domain, and a cytoplasmic domain. PD-L2 shares considerable sequence homology with other B7 proteins, but it does not contain the putative binding sequence for CD28/CTLA4, namely SQDXXXELY or XXXYXXRT. The crystal structure of murine PD-L2 bound to murine PD-1 has been determined. as well as the structure of the hPD-L2/mutant hPD-1 complex. Expressi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PD-L1
Programmed death-ligand 1 (PD-L1) also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1) is a protein that in humans is encoded by the ''CD274'' gene. Programmed death-ligand 1 (PD-L1) is a 40kDa type 1 transmembrane protein that has been speculated to play a major role in suppressing the adaptive arm of immune systems during particular events such as pregnancy, tissue allografts, autoimmune disease and other disease states such as hepatitis. Normally the adaptive immune system reacts to antigens that are associated with immune system activation by exogenous or endogenous danger signals. In turn, clonal expansion of antigen-specific CD8+ T cells and/or CD4+ helper cells is propagated. The binding of PD-L1 to the inhibitory checkpoint molecule PD-1 transmits an inhibitory signal based on interaction with phosphatases (SHP-1 or SHP-2) via Immunoreceptor Tyrosine-Based Switch Motif (ITSM). This reduces the proliferation of antigen-specific T-cells in lymph nod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B7 Family Ligands And CD28 Family Receptors
B7, B.VII, B07 or B-7 may refer to: Vehicles and transportation * Alpina B7, a luxury sedan * B07, a type of train in London; see Docklands Light Railway rolling stock * B7 (New York City bus), serving Brooklyn * Bundesstraße 7, a German Bundesstraße (Federal Highway) * Bavarian B VII, an 1868 German experimental locomotive * NSB B7 (Class 7), Norwegian railway carriages * HMS ''B7'', a B-class submarine of the Royal Navy * Blackburn B-7, a British aircraft * Lohner B.VII, an aircraft * Douglas Y1B-7, a bomber of the United States Army Air Corps * UNI Airways (Taiwan) IATA airline designator * Boeing 777 * Bensen B-7, a 1955 United States small rotor kite Science * B7 (protein), a protein in the immune system * HLA-B7, an HLA-B serotype * Vitamin B7, another name for biotin * A subclass of B- class stars * Boron-7 (B-7 or 7B), an isotope of boron Other * B7, a diesel fuel containing 7% biodiesel * B7, the second highest note on a piano, nearly two octaves above Soprano C * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knockout Mouse
A knockout mouse, or knock-out mouse, is a genetically modified mouse (''Mus musculus'') in which researchers have inactivated, or "knocked out", an existing gene by replacing it or disrupting it with an artificial piece of DNA. They are important animal models for studying the role of genes which have been sequenced but whose functions have not been determined. By causing a specific gene to be inactive in the mouse, and observing any differences from normal behaviour or physiology, researchers can infer its probable function. Mice are currently the laboratory animal species most closely related to humans for which the knockout technique can easily be applied. They are widely used in knockout experiments, especially those investigating genetic questions that relate to human physiology. Gene knockout in rats is much harder and has only been possible since 2003. The first recorded knockout mouse was created by Mario R. Capecchi, Martin Evans, and Oliver Smithies in 1989, for whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-1BB Ligand
Tumor necrosis factor ligand superfamily member 9 also known as 4-1BB ligand or 4-1BBL or CD137L is a protein that in humans is encoded by the TNFSF9 gene. 4-1BBL is a type 2 transmembrane glycoprotein receptor that is found on APCs (antigen presenting cells) and binds to 4-1BB (also known as CD137). The 4-1BB/4-1BBL complex belongs to the TNFR:TNF superfamily, which is expressed on activated T Lymphocytes. Structure of 4-1BB/4-1BBL complex The 4-1BB/4-1BBL complex consists of three monomeric 4-1BBs bound to a trimeric 4-1BBL. Each 4-1BB monomer binds to two 4-1BBLs via cysteine-rich domains (CRDs). The interaction between 4-1BB and the second 4-1BBL is required to stabilize their interactions. The link with 4-1BBL is largely made up of amino acids from the dynamic loops of the CRD2 and the β sheet of CRD3 of 4-1BB, according to a detailed study of the binding between the 4-1BB and 4-1BBL interface. CRD2 amino acids (T61, Q67, and K69) interact with the AA′ loop (Y110 and G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD137
CD137 is a member of the tumor necrosis factor (TNF) receptor family. Its alternative names are ''tumor necrosis factor receptor superfamily member 9'' (TNFRSF9), 4-1BB and ''induced by lymphocyte activation'' (ILA). It is of interest to immunologists as a co-stimulatory immune checkpoint molecule. Expression CD137 is expressed by activated T cells of both the CD4+ and CD8+ lineages. Although it is thought to function mainly in co-stimulating those cell types to support their activation by antigen presenting cells expressing its ligand (CD137L), CD137 is also expressed on dendritic cells, B cells, NK cells, neutrophils and macrophages. Specific effects on cells The best characterized activity of CD137 is its costimulatory activity for activated T cells. Crosslinking of CD137 enhances T cell proliferation, IL-2 secretion, survival and cytolytic activity. Further, it can enhance immune activity to eliminate tumors in mice. Interactions CD137 has been shown to interact with TR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumor Necrosis Factors
The tumor necrosis factor (TNF) superfamily is a protein superfamily of type II transmembrane proteins containing TNF homology domain and forming trimers. Members of this superfamily can be released from the cell membrane by extracellular proteolytic cleavage and function as a cytokine. These proteins are expressed predominantly by immune cells and they regulate diverse cell functions, including immune response and inflammation, but also proliferation, differentiation, apoptosis and embryogenesis. The superfamily contains 19 members that bind to 29 members of TNF receptor superfamily. An occurrence of orthologs in invertebrates hints at ancient origin of this superfamily in evolution. The PROSITE pattern of this superfamily is located in a beta sheet The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
