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Diacylglycerol Kinase
Diacylglycerol kinase (DGK or DAGK) is a family of enzymes that catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid (PA), utilizing ATP as a source of the phosphate. In non-stimulated cells, DGK activity is low, allowing DAG to be used for glycerophospholipid biosynthesis, but on receptor activation of the phosphoinositide pathway, DGK activity increases, driving the conversion of DAG to PA. As both lipids are thought to function as bioactive lipid signaling molecules with distinct cellular targets, DGK therefore occupies an important position, effectively serving as a switch by terminating the signalling of one lipid while simultaneously activating signalling by another. In bacteria, DGK is very small (13 to 15 kD) membrane protein which seems to contain three transmembrane domains. The best conserved region is a stretch of 12 residues which are located in a cytoplasmic loop between the second and third transmembrane domains. Some Gram-positive bacteria al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diglyceride
A diglyceride, or diacylglycerol (DAG), is a glyceride consisting of two fatty acid chains covalently bonded to a glycerol molecule through ester linkages. Two possible forms exist, 1,2-diacylglycerols and 1,3-diacylglycerols. DAGs can act as surfactants and are commonly used as emulsifiers in processed foods. DAG-enriched oil (particularly 1,3-DAG) has been investigated extensively as a fat substitute due to its ability to suppress the accumulation of body fat; with total annual sales of approximately USD 200 million in Japan since its introduction in the late 1990s till 2009. Production Diglycerides are a minor component of many seed oils and are normally present at ~1–6%; or in the case of cottonseed oil as much as 10%. Industrial production is primarily achieved by a glycerolysis reaction between triglycerides and glycerol. The raw materials for this may be either vegetable oils or animal fats. Food additive Diglycerides, generally in a mix with monoglycerides (E471), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phospholipid
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine. Phospholipids are a key component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another class of lipid, sterol, interspersed among the phospholipids. The combination provides fluidity in two dimensions combined with mechanical strength against rupture. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science. The first phospholipid identified in 1847 as such in biological tissues was lecith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDZ Domain
The PDZ domain is a common structural domain of 80-90 amino-acids found in the signaling proteins of bacteria, yeast, plants, viruses and animals. Proteins containing PDZ domains play a key role in anchoring receptor proteins in the membrane to cytoskeletal components. Proteins with these domains help hold together and organize signaling complexes at cellular membranes. These domains play a key role in the formation and function of signal transduction complexes. PDZ domains also play a highly significant role in the anchoring of cell surface receptors (such as Cftr and FZD7) to the actin cytoskeleton via mediators like NHERF and ezrin. ''PDZ'' is an initialism combining the first letters of the first three proteins discovered to share the domain — post synaptic density protein (PSD95), Drosophila disc large tumor suppressor (Dlg1), and zonula occludens-1 protein (zo-1). PDZ domains have previously been referred to as DHR (Dlg homologous region) or GLGF (glycine-leucine-glycin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Localisation Signal
A nuclear localization signal ''or'' sequence (NLS) is an amino acid sequence that 'tags' a protein for import into the cell nucleus by nuclear transport. Typically, this signal consists of one or more short sequences of positively charged lysines or arginines exposed on the protein surface. Different nuclear localized proteins may share the same NLS. An NLS has the opposite function of a nuclear export signal (NES), which targets proteins out of the nucleus. Types Classical These types of NLSs can be further classified as either monopartite or bipartite. The major structural differences between the two are that the two basic amino acid clusters in bipartite NLSs are separated by a relatively short spacer sequence (hence bipartite - 2 parts), while monopartite NLSs are not. The first NLS to be discovered was the sequence PKKKRKV in the SV40 Large T-antigen (a monopartite NLS). The NLS of nucleoplasmin, KR AATKKAGQAKKK, is the prototype of the ubiquitous bipartite signal: two clu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ankyrin
Ankyrins are a family of proteins that mediate the attachment of integral membrane proteins to the spectrin-actin based membrane cytoskeleton. Ankyrins have binding sites for the beta subunit of spectrin and at least 12 families of integral membrane proteins. This linkage is required to maintain the integrity of the plasma membranes and to anchor specific ion channels, ion exchangers and ion transporters in the plasma membrane. The name is derived from the Greek word ἄγκυρα (''ankyra'') for "anchor". Structure Ankyrins contain four functional domains: an N-terminal domain that contains 24 tandem ankyrin repeats, a central domain that binds to spectrin, a death domain that binds to proteins involved in apoptosis, and a C-terminal regulatory domain that is highly variable between different ankyrin proteins. Membrane protein recognition The 24 tandem ankyrin repeats are responsible for the recognition of a wide range of membrane proteins. These 24 repeats contain 3 struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MARCKS
Myristoylated alanine-rich C-kinase substrate is a protein that in humans is encoded by the ''MARCKS'' gene. It plays important roles in cell shape, cell motility, secretion, transmembrane transport, regulation of the cell cycle, and neural development. Recently, MARCKS has been implicated in the exocytosis of a number of vesicles and granules such as mucin and chromaffin. It is also the name of a protein family, of which MARCKS is the most studied member. They are intrinsically disordered proteins, with an acidic pH, with high proportions of alanine, glycine, proline, and glutamic acid. They are membrane-bound through a lipid anchor at the N-terminus, and a polybasic domain in the middle. They are regulated by Ca2+/calmodulin and protein kinase C. In their unphosphorylated form, they bind to actin filaments, causing them to crosslink, and sequester acidic membrane phospholipids such as PIP2. The protein encoded by this gene is a substrate for protein kinase C. It is localized to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arachidonate
Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6), or 20:4(5,8,11,14). It is structurally related to the saturated arachidic acid found in cupuaçu butter. Its name derives from the New Latin word ''arachis'' (peanut), but peanut oil does not contain any arachidonic acid. Chemistry In chemical structure, arachidonic acid is a carboxylic acid with a 20-carbon chain and four ''cis''-double bonds; the first double bond is located at the sixth carbon from the omega end. Some chemistry sources define 'arachidonic acid' to designate any of the eicosatetraenoic acids. However, almost all writings in biology, medicine, and nutrition limit the term to ''all cis''-5,8,11,14-eicosatetraenoic acid. Biology Arachidonic acid is a polyunsaturated fatty acid present in the phospholipids (especially phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositides) of membranes of the body's cells, and is abundant in the brain, muscles, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleckstrin Homology
Pleckstrin homology domain (PH domain) or (PHIP) is a protein domain of approximately 120 amino acids that occurs in a wide range of proteins involved in intracellular signaling or as constituents of the cytoskeleton. This domain can bind phosphatidylinositol lipids within biological membranes (such as phosphatidylinositol (3,4,5)-trisphosphate and phosphatidylinositol (4,5)-bisphosphate), and proteins such as the βγ-subunits of heterotrimeric G proteins, and protein kinase C. Through these interactions, PH domains play a role in recruiting proteins to different membranes, thus targeting them to appropriate cellular compartments or enabling them to interact with other components of the signal transduction pathways. Lipid binding specificity Individual PH domains possess specificities for phosphoinositides phosphorylated at different sites within the inositol ring, e.g., some bind phosphatidylinositol (4,5)-bisphosphate but not phosphatidylinositol (3,4,5)-trisphosphate or ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EF-hand
The EF hand is a helix–loop–helix structural domain or ''motif'' found in a large family of calcium-binding proteins. The EF-hand motif contains a helix–loop–helix topology, much like the spread thumb and forefinger of the human hand, in which the Ca2+ ions are coordinated by ligands within the loop. The motif takes its name from traditional nomenclature used in describing the protein parvalbumin, which contains three such motifs and is probably involved in muscle relaxation via its calcium-binding activity. The EF-hand consists of two alpha helices linked by a short loop region (usually about 12 amino acids) that usually binds calcium ions. EF-hands also appear in each structural domain of the signaling protein calmodulin and in the muscle protein troponin-C. Calcium ion binding site The calcium ion is coordinated in a pentagonal bipyramidal configuration. The six residues involved in the binding are in positions 1, 3, 5, 7, 9 and 12; these residues are denoted by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometimes the symbol Cyz is used. The deprotonated form can generally be described by the symbol Cym as well. The thiol is susceptible to oxidation to give the disulfide derivative cystine, which serves an important structural role in many proteins. In this case, the symbol Cyx is sometimes used. When used as a food additive, it has the E number E920. Cysteine is encoded by the codons UGU and UGC. The sulfur-containing amino acids cysteine and methionine are more easily oxidized than the other amino acids. Structure Like other amino acids (not as a residue of a protein), cysteine exists as a zwitterion. Cysteine has chirality in the older / notation based on homology to - and -glyceraldehyde. In the newer ''R''/''S'' system of designating chi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipotechoic Acid
Lipoteichoic acid (LTA) is a major constituent of the cell wall of gram-positive bacteria. These organisms have an inner (or cytoplasmic) membrane and, external to it, a thick (up to 80 nanometer) peptidoglycan layer. The structure of LTA varies between the different species of Gram-positive bacteria and may contain long chains of ribitol or glycerol phosphate. LTA is anchored to the cell membrane via a diacylglycerol. It acts as regulator of autolytic wall enzymes (muramidases). It has antigenic properties being able to stimulate specific immune response.Lipoteichoic acid's chemical signals is C28H74O37P3=OH. LTA may bind to target cells non-specifically through membrane phospholipids, or specifically to CD14 and to Toll-like receptors. Binding to TLR-2 has shown to induce NF-κB expression(a central transcription factor), elevating expression of both pro- and anti-apoptotic genes. Its activation also induces mitogen-activated protein kinases (MAPK) activation along with phosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylglycerol
Phosphatidylglycerol is a glycerophospholipid found in pulmonary surfactant and in the plasma membrane where it directly activates lipid-gated ion channels. The general structure of phosphatidylglycerol consists of a L-glycerol 3-phosphate backbone ester-bonded to either saturated or unsaturated fatty acids on carbons 1 and 2. The head group substituent glycerol is bonded through a phosphomonoester. It is the precursor of surfactant and its presence (>0.3) in the amniotic fluid of the newborn indicates fetal lung maturity. Approximately 98% of alveolar wall surface area is due to the presence of type I cells, with type II cells producing pulmonary surfactant covering around 2% of the alveolar walls. Once surfactant is secreted by the type II cells, it must be spread over the remaining type I cellular surface area. Phosphatidylglycerol is thought to be important in spreading of surfactant over the Type I cellular surface area. The major surfactant deficiency in premature infants r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
