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Bradykinin Receptor B2
Bradykinin receptor B2 is a G-protein coupled receptor for bradykinin, encoded by the BDKRB2 gene in humans. Mechanism The B2 receptor (B2R) is a G protein-coupled receptor, probably coupled to Gq and Gi. A 2022 ''Nature'' cryo-EM study of human B2R-Gq complexes by Jinkeng Sheng et al. investigated the proximal activation mechanisms of B2R. Sheng et al. propose that upon B2R binding bradykinin or kallidin to a "bulky orthosteric binding pocket," the phenylalanine F8 or F9 residue of bradykinin or kallidin respectively interacts with a "conserved toggle switch" W283. This hydrophobic interaction facilitates the outward movement of transmembrane domain 6 (TM6) of B2R on the cytoplasmic side of the membrane, as well as outward movement of F279, a key residue within the conserved PIF motif of GPCRs (involving proline, isoleucine and phenylalanine). This rearrangement of the PIF motif disrupts the ionic lock formed by the DRY motif and pushes the NPxxY motif towards the activat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-protein Coupled Receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large protein family, group of evolutionarily related proteins that are cell surface receptors that detect molecules outside the cell (biology), cell and activate cellular responses. They are coupled with G proteins. They pass through the cell membrane seven times in the form of six loops (three extracellular loops interacting with ligand molecules, three intracellular loops interacting with G proteins, an N-terminus, N-terminal extracellular region and a C-terminal intracellular region) of amino acid residues, which is why they are sometimes referred to as seven-transmembrane receptors. Text was copied from this source, which is available under Attribution 2.5 Generic (CC BY 2.5) licence/ref> Ligands can bind either to the extracellular N-terminus and loops (e.g. glutama ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenylate Cyclase
Adenylate cyclase (EC 4.6.1.1, also commonly known as adenyl cyclase and adenylyl cyclase, abbreviated AC) is an enzyme with systematic name ATP diphosphate-lyase (cyclizing; 3′,5′-cyclic-AMP-forming). It catalyzes the following reaction: :ATP = 3′,5′-cyclic AMP + diphosphate It has key regulatory roles in essentially all cells. It is the most polyphyletic known enzyme: six distinct classes have been described, all catalyzing the same reaction but representing unrelated gene families with no known sequence or structural homology. The best known class of adenylyl cyclases is class III or AC-III (Roman numerals are used for classes). AC-III occurs widely in eukaryotes and has important roles in many human tissues. All classes of adenylyl cyclase catalyse the conversion of adenosine triphosphate (ATP) to 3',5'-cyclic AMP (cAMP) and pyrophosphate. Magnesium ions are generally required and appear to be closely involved in the enzymatic mechanism. The cAMP produced by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nociception
In physiology, nociception , also nocioception; ) is the Somatosensory system, sensory nervous system's process of encoding Noxious stimulus, noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal to trigger an appropriate defensive response. In nociception, intense chemical (e.g., capsaicin present in chili pepper or cayenne pepper), mechanical (e.g., cutting, crushing), or thermal (heat and cold) stimulation of sensory neurons called nociceptors produces a signal that travels along a chain of nerve fibers to the brain. Nociception triggers a variety of physiological and behavioral responses to protect the organism against an aggression, and usually results in a subjective experience, or perception, of pain in Sentience, sentient beings. Detection of noxious stimuli Potentially damaging mechanical, thermal, and chemical stimuli are detecte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smooth Muscle
Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It can be divided into two subgroups, ''single-unit'' and ''multi-unit'' smooth muscle. Within single-unit muscle, the whole bundle or sheet of smooth muscle cells contracts as a syncytium. Smooth muscle is found in the walls of hollow organs, including the stomach, intestines, bladder and uterus. In the walls of blood vessels, and lymph vessels, (excluding blood and lymph capillaries) it is known as vascular smooth muscle. There is smooth muscle in the tracts of the respiratory, urinary, and reproductive systems. In the eyes, the ciliary muscles, iris dilator muscle, and iris sphincter muscle are types of smooth muscles. The iris dilator and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edema
Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin that feels tight, the area feeling heavy, and joint stiffness. Other symptoms depend on the underlying cause. Causes may include Chronic venous insufficiency, venous insufficiency, heart failure, kidney problems, hypoalbuminemia, low protein levels, liver problems, deep vein thrombosis, infections, kwashiorkor, angioedema, certain medications, and lymphedema. It may also occur in immobile patients (stroke, spinal cord injury, aging), or with temporary immobility such as prolonged sitting or standing, and during menstruation or pregnancy. The condition is more concerning if it starts suddenly, or pain or shortness of breath is present. Treatment depends on the underlying cause. If the underlying mechanism involve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vasodilation
Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel walls are composed of endothelial tissue and a basal membrane lining the lumen of the vessel, concentric smooth muscle layers on top of endothelial tissue, and an adventitia over the smooth muscle layers. Relaxation of the smooth muscle layer allows the blood vessel to dilate, as it is held in a semi-constricted state by sympathetic nervous system activity. Vasodilation is the opposite of vasoconstriction, which is the narrowing of blood vessels. When blood vessels dilate, the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output. Vascular resistance is the amount of force circulating blood must overcome in order to allow perfusion of body tissues. Narrow vessels create more vascular resista ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (carboxyl g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icatibant
Icatibant, sold under the brand name Firazyr, is a medication for the symptomatic treatment of acute attacks of hereditary angioedema (HAE) in adults with C1-esterase-inhibitor deficiency. It is not effective in angioedema caused by medication from the ACE inhibitor class. It is a peptidomimetic consisting of ten amino acids, which is a selective and specific antagonist of bradykinin B2 receptors. Mechanism of action Bradykinin is a peptide-based hormone that is formed locally in tissues, very often in response to a trauma. It increases vessel permeability, dilates blood vessels and causes smooth muscle cells to contract. Bradykinin plays an important role as the mediator of pain. Surplus bradykinin is responsible for the typical symptoms of inflammation, such as swelling, redness, overheating and pain. These symptoms are mediated by activation of bradykinin B2 receptors. Icatibant acts as a bradykinin inhibitor by blocking the binding of native bradykinin to the bradykini ... [...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] |
Angiotensin (1-7)
Angiotensin (1-7) (; Molecular weight = 899.02 g/mol; H- Asp- Arg- Val- Tyr-Ile-His-Pro-OH) is an active heptapeptide of the renin–angiotensin system (RAS). It also known by the generic name talfirastide (development name TXA127). In 1988, Santos ''et al'' demonstrated that angiotensin (1-7) was a main product of the incubation of angiotensin I with brain micropunch biopsies and Schiavone ''et al'' reported the first biological effect of this heptapeptide. Benter et al were the first to report that Ang-(1-7) behaves in a way opposite to that of Ang II and that intavenous administration of Ang-(1-7) produces blood pressure lowering effects by activating its own receptor Angiotensin (1-7) is a vasodilator agent affecting cardiovascular organs, such as heart, blood vessels and kidneys, with functions frequently opposed to those attributed to the major effector component of the RAS, angiotensin II (Ang II). Synthesis The polypeptide Ang I can be converted into Ang (1-7) by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinin–kallikrein System
The kinin–kallikrein system or simply kinin system is a poorly understood hormonal system with limited available research. It consists of blood proteins that play a role in inflammation, blood pressure control, coagulation and pain. Its important mediators bradykinin and kallidin are vasodilators and act on many cell types. Clinical symptoms include marked weakness, tachycardia, fever, leukocytosis and acceleration of ESR. History The system was discovered in 1909 when researchers discovered that injection with urine (high in kinins) led to hypotension (low blood pressure). The researchers Emil Karl Frey, Heinrich Kraut and Eugen Werle discovered high-molecular weight kininogen in urine around 1930. Etymology kinin kkīn(eîn) to move, set in motion. kallikrein k kalli~ sweet and krein = kreos, flesh, named for the pancreatic extracts where it was first discovered Members The system consists of a number of large proteins, some small polypeptides and a group of enzymes th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
