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TLR11
Toll-like receptor 11 (TLR11) is a protein that in mice and rats is encoded by the gene ''TLR11'', whereas in humans it is represented by a pseudogene. TLR11 belongs to the toll-like receptor (TLR) family and the interleukin-1 receptor/toll-like receptor superfamily. In mice, TLR11 has been shown to recognise (bacterial) flagellin and (eukaryotic) profilin present on certain microbes, it helps propagate a host immune response. TLR11 plays a fundamental role in both the innate and adaptive immune responses, through the activation of Tumor necrosis factor-alpha, the Interleukin 12 (IL-12) response, and Interferon-gamma (IFN-gamma) secretion. TLR11 mounts an immune response to multiple microbes, including ''Toxoplasma gondii'' (''T. gondii''), ''Salmonella'' species, and uropathogenic ''E. coli'', and likely many other species due to the highly conserved nature of flagellin and profilin. Structure and localization Proteins in the TLR family are pattern recognition receptors whose ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toll-like Receptor
Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are Bitopic protein, single-pass membrane-spanning Receptor (biochemistry), receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes. Once these microbes have reached physical barriers such as the skin or intestinal tract mucosa, they are recognized by TLRs, which activate immune cell responses. The TLRs include TLR1, TLR2, TLR3, TLR4, TLR5, TLR6, TLR7, TLR8, TLR9, TLR10, TLR11, TLR12, and TLR13. Humans lack genes for TLR11, TLR12 and TLR13 and mice lack a functional gene for TLR10. TLR1, TLR2, TLR4, TLR5, TLR6, and TLR10 are located on the cell membrane, whereas TLR3, TLR7, TLR8, and TLR9 are located in Intracellular receptor, intracellular Vesicle (biology and chemistry), vesicles (because they are sensors of nucleic acids). TLRs received their name from their similarity to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pattern Recognition Receptors
Pattern recognition receptors (PRRs) play a crucial role in the proper function of the innate immune system. PRRs are germline-encoded host sensors, which detect molecules typical for the pathogens. They are proteins expressed, mainly, by cells of the innate immune system, such as dendritic cells, macrophages, monocytes, neutrophils and epithelial cells, to identify two classes of molecules: pathogen-associated molecular patterns (PAMPs), which are associated with microbial pathogens, and damage-associated molecular patterns (DAMPs), which are associated with components of host's cells that are released during cell damage or death. They are also called primitive pattern recognition receptors because they evolved before other parts of the immune system, particularly before adaptive immunity. PRRs also mediate the initiation of antigen-specific adaptive immune response and release of inflammatory cytokines. The microbe-specific molecules that are recognized by a given PRR are called p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellin
Flagellin is a globular protein that arranges itself in a hollow cylinder to form the filament in a bacterial flagellum. It has a mass of about 30,000 to 60,000 daltons. Flagellin is the principal component of bacterial flagella, and is present in large amounts on nearly all flagellated bacteria. Structure The structure of flagellin is responsible for the helical shape of the flagellar filament, which is important for its proper function. It is transported through the center of the filament to the tip where it polymerases spontaneously into a part of the filament. It is unfolded by the FliS () flagellar secretion chaperone during transport. The filament is made up of eleven smaller "protofilaments", nine of which contains flagellin in the L-type shape and the other two in the R-type shape. The helical N- and C-termini of flagellin form the inner core of the flagellin protein, and is responsible for flagellin's ability to polymerize into a filament. The middle residues make ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxoplasma Gondii Tachy
''Toxoplasma gondii'' () is an obligate intracellular parasitic protozoan (specifically an apicomplexan) that causes toxoplasmosis. Found worldwide, ''T. gondii'' is capable of infecting virtually all warm-blooded animals, but felids, such as domestic cats, are the only known definitive hosts in which the parasite may undergo sexual reproduction. ''T. gondii'' has been shown to alter the behavior of infected rodents in ways that increase the rodents' chances of being preyed upon by felids. Support for this "manipulation hypothesis" stems from studies showing that ''T. gondii''-infected rats have a decreased aversion to cat urine. Because cats are the only hosts within which ''T. gondii'' can sexually reproduce to complete and begin its lifecycle, such behavioral manipulations are thought to be evolutionary adaptations that increase the parasite's reproductive success. Rats that do not avoid cat habitations will more likely become cat prey. ''Toxoplasma gondii'' infection i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stop Codon
In molecular biology (specifically protein biosynthesis), a stop codon (or termination codon) is a codon (nucleotide triplet within messenger RNA) that signals the termination of the translation process of the current protein. Most codons in messenger RNA correspond to the addition of an amino acid to a growing polypeptide chain, which may ultimately become a protein; stop codons signal the termination of this process by binding release factors, which cause the ribosomal subunits to disassociate, releasing the amino acid chain. While start codons need nearby sequences or initiation factors to start translation, a stop codon alone is sufficient to initiate termination. Properties Standard codons In the standard genetic code, there are three different termination codons: Alternative stop codons There are variations on the standard genetic code, and alternative stop codons have been found in the mitochondrial genomes of vertebrates, ''Scenedesmus obliquus'', and '' Thra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemokine
Chemokines (), or chemotactic cytokines, are a family of small cytokines or signaling proteins secreted by cells that induce directional movement of leukocytes, as well as other cell types, including endothelial and epithelial cells. In addition to playing a major role in the activation of host immune responses, chemokines are important for biological processes, including morphogenesis and wound healing, as well as in the pathogenesis of diseases like cancers. Cytokine proteins are classified as chemokines according to behavior and structural characteristics. In addition to being known for mediating chemotaxis, chemokines are all approximately 8-10 kilodaltons in mass and have four cysteine residues in conserved locations that are key to forming their 3-dimensional shape. These proteins have historically been known under several other names including the ''SIS family of cytokines'', ''SIG family of cytokines'', ''SCY family of cytokines'', ''Platelet factor-4 superfamily'' or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Co-stimulation
Co-stimulation is a secondary signal which immune cells rely on to activate an immune response in the presence of an antigen-presenting cell. In the case of T cells, two stimuli are required to fully activate their immune response. During the activation of lymphocytes, co-stimulation is often crucial to the development of an effective immune response. Co-stimulation is required in addition to the antigen-specific signal from their antigen receptors. T cell co-stimulation T cells require two signals to become fully activated. A first signal, which is antigen-specific, is provided through the T cell receptor (TCR) which interacts with peptide- MHC molecules on the membrane of antigen presenting cells (APC). A second signal, the co-stimulatory signal, is antigen nonspecific and is provided by the interaction between co-stimulatory molecules expressed on the membrane of APC and the T cell. One of the best characterized co-stimulatory molecules expressed by T cells is CD28, which inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T Helper Cell
The T helper cells (Th cells), also known as CD4+ cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are considered essential in B cell antibody class switching, breaking cross-tolerance in dendritic cells, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages and neutrophils. CD4+ cells are mature Th cells that express the surface protein CD4. Genetic variation in regulatory elements expressed by CD4+ cells determines susceptibility to a broad class of autoimmune diseases. Structure and function Th cells contain and release cytokines to aid other immune cells. Cytokines are small protein mediators that alter the behavior of target cells that express receptors for those cytokines. These cells help polarize the immune response depending on the nature of the immunological insult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudogene
Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by Reverse transcriptase, reverse transcription of an mRNA transcript. Pseudogenes are usually identified when genome sequence analysis finds gene-like sequences that lack regulatory sequences needed for Transcription (biology), transcription or Translation (biology), translation, or whose coding sequences are obviously defective due to Frameshift mutation, frameshifts or premature stop codons. Most non-bacterial genomes contain many pseudogenes, often as many as functional genes. This is not surprising, since various biological processes are expected to accidentally create pseudogenes, and there are no specialized mechanisms to remove them from genomes. Eventually pseudogenes may be deleted from their genomes by chance DNA replication or DNA repair errors, or they may accumulate so many mutational cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apicomplexa
The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. The organelle is an adaptation that the apicomplexan applies in penetration of a host cell. The Apicomplexa are unicellular and spore-forming. All species are obligate endoparasites of animals, except '' Nephromyces'', a symbiont in marine animals, originally classified as a chytrid fungus. Motile structures such as flagella or pseudopods are present only in certain gamete stages. The Apicomplexa are a diverse group that includes organisms such as the coccidia, gregarines, piroplasms, haemogregarines, and plasmodia. Diseases caused by Apicomplexa include: * Babesiosis (''Babesia'') * Malaria (''Plasmodium'') * Cryptosporidiosis (''Cryptosporidium parvum'') * Cyclosporiasis (''Cyclospora cayetanensis'') * Cystoisosporiasis (''Cystoisosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dendritic Cell
Dendritic cells (DCs) are antigen-presenting cells (also known as ''accessory cells'') of the mammalian immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and the adaptive immune systems. Dendritic cells are present in those tissues that are in contact with the external environment, such as the skin (where there is a specialized dendritic cell type called the Langerhans cell) and the inner lining of the nose, lungs, stomach and intestines. They can also be found in an immature state in the blood. Once activated, they migrate to the lymph nodes where they interact with T cells and B cells to initiate and shape the adaptive immune response. At certain development stages they grow branched projections, the ''dendrites'' that give the cell its name (δένδρον or déndron being Greek for 'tree'). While similar in appearance, these are structures ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxoplasmosis
Toxoplasmosis is a parasitic disease caused by ''Toxoplasma gondii'', an apicomplexan. Infections with toxoplasmosis are associated with a variety of neuropsychiatric and behavioral conditions. Occasionally, people may have a few weeks or months of mild, flu-like illness such as muscle aches and tender lymph nodes. In a small number of people, eye problems may develop. In those with a weak immune system, severe symptoms such as seizures and poor coordination may occur. If a person becomes infected during pregnancy, a condition known as congenital toxoplasmosis may affect the child. Toxoplasmosis is usually spread by eating poorly cooked food that contains cysts, exposure to infected cat feces, and from an infected woman to their baby during pregnancy. Rarely, the disease may be spread by blood transfusion. It is not otherwise spread between people. The parasite is known to reproduce sexually only in the cat family. However, it can infect most types of warm-blooded animals, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
