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C3b Receptor
C3b is the larger of two elements formed by the cleavage of complement component 3, and is considered an important part of the innate immune system. C3b is potent in opsonization: tagging pathogens, immune complexes ( antigen- antibody), and apoptotic cells for phagocytosis. Additionally, C3b plays a role in forming a C3 convertase when bound to Factor B (C3bBb complex), or a C5 convertase when bound to C4b and C2b (C4b2b3b complex) or when an additional C3b molecule binds to the C3bBb complex (C3bBb3b complex). C3b's ability to perform these important functions derives from its ability to covalently bind to the surface of invading pathogens within an organism's body. The cleavage of C3 leaves C3b with an exposed thioester bond, allowing C3b to effectively coat and tag foreign cells by covalently binding to hydroxyl (-OH) and amine (-NH2) groups on foreign cell surfaces. This cleavage can occur via three mechanisms (classical pathway, alternative pathway and lectin pathway) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Pathway
A complement is something that completes something else. Complement may refer specifically to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-class collections into complementary sets * Complementary color, in the visual arts Biology and medicine *Complement system (immunology), a cascade of proteins in the blood that form part of innate immunity *Complementary DNA, DNA reverse transcribed from a mature mRNA template *Complementarity (molecular biology), a property whereby double stranded nucleic acids pair with each other *Complementation (genetics), a test to determine if independent recessive mutant phenotypes are caused by mutations in the same gene or in different genes Grammar and linguistics * Complement (linguistics), a word or phrase having a particular syntactic role ** Subject complement, a word or phrase adding to a clause's subject after a linking verb * Phonetic com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoglobulin G
Immunoglobulin G (Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG antibody has two paratopes. Function Antibodies are major components of humoral immunity. IgG is the main type of antibody found in blood and extracellular fluid, allowing it to control infection of body tissues. By binding many kinds of pathogens such as viruses, bacteria, and fungi, IgG protects the body from infection. It does this through several mechanisms: * IgG-mediated binding of pathogens causes their immobilization and binding together via agglutination; IgG coating of pathogen surfaces (known as opsonization) allows their recognition and ingestion by phagocytic immune cells leading to the elimination of the pathogen itself; * IgG activates all the classical pathway of the complement system, a cascade of immune protein pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutrophil Granulocyte
Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in different animals. They are formed from stem cells in the bone marrow and differentiated into subpopulations of neutrophil-killers and neutrophil-cagers. They are short-lived and highly mobile, as they can enter parts of tissue where other cells/molecules cannot. Neutrophils may be subdivided into segmented neutrophils and banded neutrophils (or bands). They form part of the polymorphonuclear cells family (PMNs) together with basophils and eosinophils. The name ''neutrophil'' derives from staining characteristics on hematoxylin and eosin ( H&E) histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink. Normal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrophage
Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer cells, microbes, cellular debris, and foreign substances, which do not have proteins that are specific to healthy body cells on their surface. The process is called phagocytosis, which acts to defend the host against infection and injury. These large phagocytes are found in essentially all tissues, where they patrol for potential pathogens by amoeboid movement. They take various forms (with various names) throughout the body (e.g., histiocytes, Kupffer cells, alveolar macrophages, microglia, and others), but all are part of the mononuclear phagocyte system. Besides phagocytosis, they play a critical role in nonspecific defense (innate immunity) and also help initiate specific defense mechanisms (adaptive immunity) by recruiting other immune ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Receptor 1
Complement receptor type 1 (CR1) also known as C3b/C4b receptor or CD35 (cluster of differentiation 35) is a protein that in humans is encoded by the ''CR1'' gene. This gene is a member of the regulators of complement activation (RCA) family and is located in the 'cluster RCA' region of chromosome 1. The gene encodes a monomeric single-pass type I membrane glycoprotein found on erythrocytes, leukocytes, glomerular podocytes, hyalocytes, and splenic follicular dendritic cells. The Knops blood group system is a system of antigens located on this protein. The protein mediates cellular binding to particles and immune complexes that have activated complement. Decreases in expression of this protein and/or mutations in its gene have been associated with gallbladder carcinomas, mesangiocapillary glomerulonephritis, systemic lupus erythematosus and sarcoidosis. Mutations in this gene have also been associated with a reduction in ''Plasmodium falciparum'' rosetting, conferring protectio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Properdin
Properdin is protein that in humans is encoded by the CFP (complement factor properdin) gene. Properdin is plasma glycoprotein that activates the complement system of the innate immune system. This protein binds to bacterial cell walls and dying human cells to stabilize the C3 and C5-convertase enzyme complexes to form an attack complex that lead to the lysis of the cell. Structure Properdin is a gamma globulin protein composed of multiple identical protein subunits with a separate ligand-binding site. Native properdin occurs in head-to-tail dimers, trimers and tetramers in the fixed ratio 22:52:28. Function It is known that it participates in some specific immune responses. It plays a part in tissue inflammation as well as the engulfing of pathogens by phagocytes. In addition it is known to help to neutralize some viruses. The properdin promotes the association of C3b with Factor B and provides a focal point for the assembly of C3bBb on a surface. It binds to preformed alte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor D
Factor D (, ''C3 proactivator convertase'', ''properdin factor D esterase'', ''factor D (complement)'', ''complement factor D'', ''CFD'', ''adipsin'') is a protein which in humans is encoded by the ''CFD'' gene. Factor D is involved in the alternative complement pathway of the complement system where it cleaves factor B. Function The protein encoded by this gene is a member of the trypsin family of serine proteases secreted by adipocytes into the bloodstream. The encoded protein is a component of the alternative complement pathway best known for its role in humoral suppression of infectious agents. Finally, the encoded protein has a high level of expression in fat, suggesting a role for adipose tissue in immune system biology. Factor D is a serine protease that stimulates glucose transport for triglyceride accumulation in fats cells and inhibits lipolysis. Clinical significance The level of Factor D is decreased in obese patients. This reduction may be due to high activit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Component 9
Complement component 9 (C9) is a MACPF protein involved in the complement system, which is part of the innate immune system. Once activated, about 12-18 molecules of C9 polymerize to form pores in target cell membranes, causing lysis and cell death. C9 is one member of the complement membrane attack complex (MAC), which also includes complement components C5b, C6, C7 and C8. The formation of the MAC occurs through three distinct pathways: the classical, alternative, and lectin pathways. Pore formation by C9 is an important way that bacterial cells are killed during an infection, and the target cell is often covered in multiple MACs. The clinical impact of a deficiency in C9 is an infection with the gram-negative bacterium ''Neisseria meningitidis.'' Structure C9 genes include 11 exons and 10 introns An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C8 Complex
Complement component 8 is a protein involved in the complement system. It is part of the membrane attack complex (MAC). A hereditary deficiency of C8 can result in increased susceptibility to Neisseria infections, such as meningitis and gonorrhea Gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium ''Neisseria gonorrhoeae''. Infection may involve the genitals, mouth, or rectum. Infected men may experience pain or burning with u .... Structure C8 is a heterotrimer; it consists of three different subunits. These are called C8 alpha, beta and gamma chains, encoded by the genes ''C8A'', ''C8B'' and ''C8G'' respectively. References External links * Complement system {{gene-9-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Component 7
Complement component 7 is a protein involved in the complement system of the innate immune system. C7 is part of the membrane attack complex (MAC) which creates a hole on pathogen surfaces, leading to cell lysis and death. Its primary task is to bind the C5bC6 complex together. This junction alters the configuration of the protein molecules, exposing a hydrophobic site on C7 that allows the C7 to insert into the phospholipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells. The cell membranes of almost all organisms and many vir ... of the pathogen. See also * Terminal complement pathway deficiency External links * * References Complement system {{gene-5-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Component 6
Complement component 6 is a protein that in humans is encoded by the ''C6'' gene. Complement component 6 is a protein involved in the complement system The complement system, also known as complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and at .... It is part of the membrane attack complex which can insert into the cell membrane and cause the cell to lyse. People with C6 deficiency are prone to bacterial infection. References Further reading * * * * * * * * * * * * * * * * * * * External links * Complement system {{gene-5-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Component 2
Complement C2 is a protein that in humans is encoded by the ''C2'' gene. The protein encoded by this gene is part of the classical pathway of the complement system, acting as a multi-domain serine protease. Deficiency of C2 has been associated with certain autoimmune diseases. Function In the classical and lectin pathways of complement activation, formation of the C3-convertase and C5-convertases requires binding of C2 to an activated surface-bound C4b in the presence of Mg2+; the resultant C4bC2 complex is cleaved by C1s Complement component 1s (, '' C1 esterase'', ''activated complement C1s'', ''complement C overbar 1r'', ''C1s'') is a protein involved in the complement system. C1s is part of the C1 complex. In humans, it is encoded by the ''C1S'' gene. C1s cle ... or MASP2 into C2a and C2b. It is thought that cleavage of C2 by C1s, while bound to C4b, results in a conformational rotation of C2b whereas the released C2a fragment may retain most of its original structur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
