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Kallikrein
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 for pancreas. Since then, similar enzymes have been found in the biological fluids of humans and other mammals, as well as in some snake venoms. Venom The caterpillar kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KLKB1
KLKB1 is a gene that, in humans, encodes the ''Plasma kallikrein'' protein. Function Plasma prekallikrein is a glycoprotein that participates in the surface-dependent activation of blood coagulation, fibrinolysis, kinin generation and inflammation. It is synthesized in the liver and secreted into the blood as a single polypeptide chain. Plasma prekallikrein is converted to plasma kallikrein by factor XIIa by the cleavage of an internal Arg-Ile bond. Plasma kallikrein therefore is composed of a heavy chain and a light chain held together by a disulfide bond. The heavy chain originates from the amino-terminal end of the zymogen and contains 4 tandem repeats of 90 or 91 amino acids. Each repeat harbors a novel structure called the apple domain. The heavy chain is required for the surface-dependent pro-coagulant activity of plasma kallikrein. The light chain contains the active site or catalytic domain of the enzyme and is homologous to the trypsin family of serine proteases ... [...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] |
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 inhibitors ... online database for peptidases and their inhibitorsS01.161 * {{gene-19-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prekallikrein
Prekallikrein (PK), also known as Fletcher factor, is an 85,000 Mr serine protease that complexes with high-molecular-weight kininogen. PK is the precursor of plasma kallikrein, which is a serine protease that activates kinins. PK is cleaved to produce kallikrein by activated Factor XII (Hageman factor). Structure Prekallikrein is homologous to factor XI, and similarly consists of four apple domains and a fifth, catalytic serine protease domain. The four apple domains create a disk-like platform around the base of the catalytic domain. However, unlike factor XI, prekallikrein does not form dimers. Prekallikrein is activated to form kallikrein by factor XII cleavage of a bond homologous to the corresponding bond cleaved during factor XI activation. Prekallikrein deficiency Hereditary deficiencies in PK are very rare. They can cause a prolonged APTT, which can be corrected by incubation of the patient’s plasma. Deficiencies in PK can also be acquired due to some disease st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Kallikrein
Plasma kallikrein (, ''serum kallikrein'', ''kininogenin'', ''kallikrein I'', ''kallikrein II'', ''kininogenase'', ''kallikrein'', ''callicrein'', ''glumorin'', ''padreatin'', ''padutin'', ''kallidinogenase'', ''bradykininogenase'', ''panceatic kallikrein'', ''onokrein P'', ''dilminal D'', ''depot-Padutin'', ''urokallikrein'', ''urinary kallikrein'') is an enzyme. This enzyme catalyses the following chemical reaction : Selective cleavage of some Arg- and Lys- bonds, including Lys-Arg and Arg-Ser in (human) kininogen to release bradykinin This enzyme is formed from plasma prokallikrein ( Fletcher factor) by factor XIIa. See also * Kallikrein 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 ... References External links * {{Portal bar, Biology, border=no EC 3.4.21 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kininogen
Kininogens are precursor proteins for kinins, biologically active polypeptides involved in blood coagulation, vasodilation, smooth muscle contraction, inflammatory regulation, and the regulation of the cardiovascular and renal systems. Types of kininogen There are two main types of kininogen (KNG), high-molecular-weight-kininogen and 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 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 Low-molecular-weight-kininogen (LK) is mainly a precursor protein for kallidin. LK, however, is not actively involved in blood coagulation, but its byproducts c ... [...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 inhibitors ... online database for peptidases and their inhibitorsS01.020 {{gene-19-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KLK3
Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related peptidase family and is secreted by the epithelial cells of the prostate gland. PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum and allows sperm to swim freely. It is also believed to be instrumental in dissolving cervical mucus, allowing the entry of sperm into the uterus. PSA is present in small quantities in the serum of men with healthy prostates, but is often elevated in the presence of prostate cancer or other prostate disorders. PSA is not uniquely an indicator of prostate cancer, but may also detect prostatitis or benign prostatic hyperplasia. Medical uses Prostate cancer Screening Clinical practice guidelines for prostate cancer screening vary and are controversial, in part due to uncertainty as to whether the benefits of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor XII
Coagulation factor XII, also known as Hageman factor, is a plasma protein. 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 the ''F12'' gene. 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. Its 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, and its light chain contains the protease domain. The structure of the FnI-EGF-like tandem domain of coagulation factor XII has been solved by X-ray crystallography. Crystal structures of the FXII light chain has also been determined unbound (β-FXII) and bound (β-FXIIa) to inhibitors. Factor XII (FXII, Hageman factor) is a plasma glycoprotein of approximately 90 kDa molecular weight is par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinin
A kinin is any of various structurally related polypeptides, such as bradykinin and kallidin. They are members of the autacoid family. Kinins are peptides that are cleaved from kininogens by the process of kallikreins. Kallikreins activate kinins when stimulated. It is a component of the kinin-kallikrein system. Their precursors are kininogens. Kininogens contain a 9-11 amino acid bradykinin sequence. In botany, the plant hormones known as cytokinins were first called kinins, but the name was changed to avoid confusion. Effects of Kinins Kinin are short lived peptides that cause pain sensation, arteriolar dilation, increase vascular permeability and cause contractions in smooth muscle. Kinins transmit their effects through G protein- coupled receptors. Kinin act on axons to block nervous impulses, which leads to distal muscle relaxation. Kinin are also potent nerve stimulators. which is mostly responsible for the sense of pain (and sometimes itching). Kinin increase vascular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PRCP
Lysosomal Pro-X carboxypeptidase is an enzyme that in humans is encoded by the ''PRCP'' gene. The protein encoded by this gene is a lysosomal prolylcarboxypeptidase, which cleaves C-terminal amino acids linked to proline in peptides such as angiotensin II, III and des-Arg9-bradykinin. The cleavage occurs at acidic pH, but the enzyme activity is retained with some substrates at neutral pH. This enzyme has been shown to be an activator of the cell matrix-associated prekallikrein. The importance of angiotensin II, one of the substrates of this enzyme, in regulating blood pressure and electrolyte balance suggests that this gene may be related to essential hypertension Essential hypertension (also called primary hypertension, or idiopathic hypertension) is the form of hypertension that by definition has no identifiable secondary cause. It is the most common type affecting 85% of those with high blood pressure. T .... Alternatively spliced transcript variants encoding distinct isof ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bradykinin
Bradykinin (BK) (Greek brady-, slow; -kinin, kīn(eîn) to move) is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor and makes veins constrict, via prostaglandin F2, thereby leading to leakage into capillary beds, due to the increased pressure in the capillaries. Bradykinin is a physiologically and pharmacologically active peptide of the kinin group of proteins, consisting of nine amino acids. A class of drugs called angiotensin converting enzyme inhibitors (ACE inhibitors) increase bradykinin levels by inhibiting its degradation, thereby increasing its blood pressure lowering effect. ACE inhibitors are FDA approved for the treatment of hypertension and heart failure. Structure Bradykinin, sometimes referred to as BK, is a 9-amino acid peptide chain. The amino acid sequence of bradykinin is: Arg- Pro- Pro- Gly- Phe- Ser- Pro- Phe- Arg (RPPGFSPFR). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
