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Tissue Kallikreins
Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein (encoded by ''KLKB1 gene'') has no known paralogue, while tissue kallikrein-related peptidases (''KLKs'') encode a family of fifteen closely related serine proteases. These genes are localised to chromosome 19q13, forming the largest contiguous cluster of proteases within the human genome. Kallikreins are responsible for the coordination of various physiological functions including blood pressure, semen liquefaction and skin desquamation. Occurrence In 1934, Eugen Werle reported finding a substance in the pancreas of humans and various animals in such large amounts that the pancreas could be taken for its site of origin. He named it kallikrein, by derivation from the Greek word καλλίκρεας (''kallíkreas'') 'pancreas'. Since then, similar enzymes have been found in the biological fluids of humans and other mammals, as well as in some snake ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serine Protease
Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. They are found ubiquitously in both eukaryotes and prokaryotes. Serine proteases fall into two broad categories based on their structure: chymotrypsin-like (trypsin-like) or subtilisin-like. Classification The MEROPS protease classification system counts 16 protein superfamily, superfamilies (as of 2013) each containing many protein family, families. Each superfamily uses the catalytic triad or dyad in a different protein fold and so represent convergent evolution of the catalytic mechanism. The majority belong to the S1 family of the PA clan (superfamily) of proteases. For protein superfamily, superfamilies, P: superfamily, containing a mixture of nucleophile class families, S: purely serine proteases. superfamily. Within each superfamily, protein family, families are designated by their catalytic nucl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor XII
Coagulation factor XII, also known as Hageman factor, is a plasma protein involved in coagulation. It is the zymogen form of factor XIIa (), an enzyme of the serine protease (or serine endopeptidase) class. In humans, factor XII is encoded by ''F12'' gene. Genetics The gene for factor XII is located on the tip of the long arm of the fifth chromosome (5q33-qter). Structure Human Factor XII is 596 amino acids long and consists of two chains, the heavy chain (353 residues) and light chain (243 residues) held together by a disulfide bond. It is 80,000 daltons in molecular weight. The heavy chain contains two fibronectin-type domains (type I and II), two epidermal growth factor-like domains, a kringle domain, and a proline-rich region, while the light chain contains the protease domain. FXII can be cleaved sequentially at two sites, Arg353 and Arg334, with the second cleavage liberating the light chain and forming β-FXIIa. The structure of the FnI-EGF-like tandem domain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KLK12
Kallikrein-12 is a protein that in humans is encoded by the ''KLK12'' gene. Kallikreins are a subgroup of serine proteases having diverse physiological functions. Growing evidence suggests that many kallikreins are implicated in carcinogenesis and some have potential as novel cancer and other disease biomarkers. This gene is one of the fifteen kallikrein subfamily members located in a cluster on chromosome 19. Alternate splicing of this gene results in three transcript variants encoding different isoforms. References Further reading * * * * * * * * * * * External links * The MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ... online database for peptidases and their inhibitorsS01.020 {{gene-19-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KLK2
Kallikrein-2 is a protein that in humans is encoded by the ''KLK2'' gene, and is particularly associated with prostatic tissue. References Further reading * * * * * * * * * * * * * * * * * * * External links * The MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ... online database for peptidases and their inhibitorsS01.161 * {{gene-19-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KLK1
Kallikrein-1 is a protein that in humans is encoded by the ''KLK1'' gene. KLK1 is a member of the peptidase S1 family. Kallikreins are a subgroup of serine proteases having diverse physiological functions. Growing evidence suggests that many kallikreins are implicated in carcinogenesis and some have potential as novel cancer and other disease biomarkers. This gene is one of the fifteen kallikrein subfamily members located in a cluster on chromosome 19. This protein is functionally conserved in its capacity to release the vasoactive peptide, Lys-bradykinin, from low molecular weight kininogen. See also * Kinin–kallikrein system * Kininogen 1 References Further reading * * * * * * * * * * * * * * * * * * * External links * The MEROPS online database for peptidases and their inhibitorsS01.160 Proteases EC 3.1.21 {{gene-19-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PAN Domain
PAN domains have significant functional versatility fulfilling diverse biological roles by mediating protein-protein and protein-carbohydrate interactions. These domains contain a hair-pin loop like structure, similar to that found in knottins but with a different pattern of disulfide bonds. It has been shown that the N-terminal domains of members of the plasminogen/hepatocyte growth factor family, the apple domains of the plasma prekallikrein/ coagulation factor XI family, and domains of various nematode proteins belong to the same module superfamily, the PAN module. The PAN domain contains a conserved core of three disulfide bridges. In some members of the family there is an additional fourth disulfide bridge that links the N- and C-termini of the domain. The apple domain, as well as other examples of the PAN domain, consists of seven β-strands that fold into a curved antiparallel sheet cradling an α-helix An alpha helix (or α-helix) is a sequence of amino acids i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor XI
Factor XI, or plasma thromboplastin antecedent, is the zymogen form of factor XIa, one of the enzymes involved in coagulation. Like many other coagulation factors, it is a serine protease. In humans, factor XI is encoded by ''F11'' gene. Function Factor XI (FXI) is produced by the liver and circulates as a homo-dimer in its inactive form. The plasma half-life of FXI is approximately 52 hours. The zymogen factor is activated into ''factor XIa'' by factor XIIa (FXIIa), thrombin, and FXIa itself; due to its activation by FXIIa, FXI is a member of the "contact pathway" (which includes HMWK, prekallikrein, factor XII, factor XI, and factor IX). Factor XIa activates factor IX by selectively cleaving arg- ala and arg- val peptide bonds. Factor IXa, in turn, forms a complex with Factor VIIIa (FIXa-FVIIIa) and activates factor X. Physiological inhibitors of factor XIa include protein Z-dependent protease inhibitor (ZPI, a member of the serine protease inhibitor/serpin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibrinolysis
Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other cause. In fibrinolysis, a fibrin clot, the product of coagulation, is broken down. Its main enzyme plasmin cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteases or by the kidney and liver. Physiology Plasmin is produced in an inactive form, plasminogen, in the liver. Although plasminogen cannot cleave fibrin, it still has an affinity for it, and is incorporated into the clot when it is formed. Tissue plasminogen activator (t-PA) and urokinase are the agents that convert plasminogen to the active plasmin, thus allowing fibrinolysis to occur. t-PA is released into the blood slowly by the damaged endothelium of the blood vessels, such that, after several days (when th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasminogen
Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is encoded by the ''PLG'' gene. Function Plasmin is a serine protease that acts to dissolve fibrin blood clots. Apart from fibrinolysis, plasmin proteolyses proteins in various other systems: It activates collagenases, some mediators of the complement system, and weakens the wall of the Graafian follicle, leading to ovulation. Plasmin is also integrally involved in inflammation. It cleaves fibrin, fibronectin, thrombospondin, laminin, and von Willebrand factor. Plasmin, like trypsin, belongs to the family of serine proteases. Plasmin is released as a zymogen called plasminogen (PLG) from the liver into the systemic circulation. Two major glycoforms of plasminogen are present in humans - type I plasminogen contains two glycosyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmin
Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin thrombus, clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is encoded by the ''PLG'' gene. Function Plasmin is a serine protease that acts to dissolve fibrin blood clots. Apart from fibrinolysis, plasmin proteolysis, proteolyses proteins in various other systems: It activates collagenases, some mediators of the complement system, and weakens the wall of the Graafian follicle, leading to ovulation. Plasmin is also integrally involved in inflammation. It cleaves fibrin, fibronectin, thrombospondin, laminin, and von Willebrand factor. Plasmin, like trypsin, belongs to the family of serine proteases. Plasmin is released as a zymogen called plasminogen (PLG) from the liver into the systemic circulation. Two major glycoforms of plasminogen are present in humans - type I plasminogen contains two g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kininogen
Kininogens are Protein precursor, precursor proteins for Kinin, kinins, biologically active Peptide, polypeptides involved in blood coagulation, vasodilation, smooth muscle contraction, Inflammation, inflammatory regulation, and the regulation of the Circulatory system, cardiovascular and Kidney, renal systems. Types of kininogen There are two main types of kininogen (KNG), High-molecular-weight kininogen, high-molecular-weight-kininogen and Low-molecular-weight kininogen, low-molecular-weight-kininogen, with a third type – T-kininogen – only found in rats but not humans. High molecular weight kininogen High-molecular-weight-kininogen (HK) is a non-enzymatic Cofactor (biochemistry), cofactor involved in the kinin-kallikrein system, which plays a role in blood coagulation, blood pressure regulation, and inflammation. It is synthesized in endothelial cells and is produced mostly by the liver. It is also a precursor protein for bradykinin. Low molecular weight kininogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kallidin
Kallidin belongs to the family kinins, which are the peptide hormones. Kallidin is a decapeptide whose sequence is H-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-OH. It can be converted to bradykinin by the aminopeptidase enzyme. Effects of Kinins Kallidin is a bioactive kinin peptide formed in response to injury from kininogen precursors through the action of kallikreins. Like all kinins, kallidin, the deca-peptide, plays an important role in several body pathologies. Kinins can regulate the blood pressure by increasing the level of vasopressor substances. They can also bind to the B1 and B2 cell surface receptors, which are G-protein coupled receptors. The mediation of the B1 receptors by des-Arg kinins as agonists can be expressed in several medical issues, such as cancer and trauma. By binding to the B2 receptors, kinins, endogenous agonists, can regulate the vasodilatation and bronchioconstriction. Chemical Mechanisms Since kinins are peptides, they can be cleaved by the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
