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PtdIns(4,5)P2
Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)''P''2, also known simply as PIP2 or PI(4,5)P2, is a minor phospholipid component of cell membranes. PtdIns(4,5)''P''2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins. PIP2 also forms lipid clusters that sort proteins. PIP2 is formed primarily by the type I phosphatidylinositol 4-phosphate 5-kinases from PI(4)P. In metazoans, PIP2 can also be formed by type II phosphatidylinositol 5-phosphate 4-kinases from PI(5)P. The fatty acids of PIP2 are variable in different species and tissues, but the most common fatty acids are stearic in position 1 and arachidonic in 2. Signaling pathways PIP2 is a part of many cellular signaling pathways, including PIP2 cycle, PI3K signalling, and PI5P metabolism. Recently, it has been found in the nucleus with unknown function. Functions Cytoskeleton dynamics near membranes PIP2 regulates the organization, polymerization, and bran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylinositol 5-phosphate
Phosphatidylinositol 5-phosphate (PtdIns5P) is a phosphoinositide, one of the phosphorylated derivatives of phosphatidylinositol (PtdIns), that are well-established membrane-anchored regulatory molecules. Phosphoinositides participate in signaling events that control cytoskeletal dynamics, intracellular membrane trafficking, cell proliferation and many other cellular functions. Generally, phosphoinositides transduce signals by recruiting specific phosphoinositide-binding proteins to intracellular membranes. Phosphatidylinositol 5-phosphate is one of the 7 known cellular phosphoinositides with less understood functions. It is phosphorylated on position D-5 of the inositol head group, which is attached via phosphodiester linkage to diacylglycerol (with varying chemical composition of the acyl chains, frequently 1-stearoyl-2-arachidonoyl chain). In quiescent cells, on average, PtdIns5P is of similar or higher abundance as compared to PtdIns3P and ~20-100-fold below the levels of PtdIn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PI(4,5)P2 Cycle
The PI(4,5)P2 cycle or simply PIP2 cycle (also known as PI cycle in past) is one of the important signalling cascades underlying many cellular functions including GPCR signaling, cytokinesis, endocytosis, and apoptosis. Signalling steps PIP2 cycle involves steps of chemical reactions characterized by various enzymes. First hydrolysis of PIP2 molecules by activated phospholipase C leads to formation of diacylglycerol and inositol trisphosphate. These two are themselves important second messengers. Diacylglycerol further converted into phosphatidic acid Phosphatidic acids are anionic phospholipids important to cell signaling and direct activation of lipid-gated ion channels. Hydrolysis of phosphatidic acid gives rise to one molecule each of glycerol and phosphoric acid and two molecules of fatty ac ... (PA) by DAGK enzyme. Furthermore, CDP-diacylglycerol synthetase uses CTP to create cytidine diphosphate diacylglycerol from PA. Generated CDP-DAG then condensed to PI by phosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Kinase B
Protein kinase B (PKB), also known as Akt, is the collective name of a set of three serine/threonine-specific protein kinases that play key roles in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, transcription, and cell migration. Family members - Isoforms There are three different genes that encode isoforms of Protein kinase B. These three genes are referred to as AKT1, AKT2, and AKT3 and encode the RAC alpha, beta, and gamma serine/threonine protein kinases respectively. The terms PKB and Akt may refer to the products of all three genes collectively, but sometimes are used to refer to PKB alpha and Akt1 alone. Akt1 is involved in cellular survival pathways, by inhibiting apoptotic processes. Akt1 is also able to induce protein synthesis pathways, and is therefore a key signaling protein in the cellular pathways that lead to skeletal muscle hypertrophy and general tissue growth. A mouse model with complete deletion of the Akt1 g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylinositol (3,4,5)-trisphosphate
Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)''P''3), abbreviated PIP3, is the product of the class I phosphoinositide 3-kinases (PI 3-kinases) phosphorylation of phosphatidylinositol (4,5)-bisphosphate (PIP2). It is a phospholipid that resides on the plasma membrane. Discovery In 1988, Lewis C. Cantley published a paper describing the discovery of a novel type of phosphoinositide kinase with the unprecedented ability to phosphorylate the 3' position of the inositol ring resulting in the formation of phosphatidylinositol-3-phosphate (PI3P). Working independently, Alexis Traynor-Kaplan and coworkers published a paper demonstrating that a novel lipid, phosphatidylinositol 3,4,5 trisphosphate (PIP3) occurs naturally in human neutrophils with levels that increased rapidly following physiologic stimulation with chemotactic peptide. Subsequent studies demonstrated that ''in vivo'' the enzyme originally identified by Cantley's group prefers PtdIns(4,5)P2 as a substrate, ... [...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 wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inositol 1,4,5-trisphosphate
Inositol trisphosphate or inositol 1,4,5-trisphosphate abbreviated InsP3 or Ins3P or IP3 is an inositol phosphate signaling molecule. It is made by hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), a phospholipid that is located in the plasma membrane, by phospholipase C (PLC). Together with diacylglycerol (DAG), IP3 is a second messenger molecule used in signal transduction in biological cells. While DAG stays inside the membrane, IP3 is soluble and diffuses through the cell, where it binds to its receptor, which is a calcium channel located in the endoplasmic reticulum. When IP3 binds its receptor, calcium is released into the cytosol, thereby activating various calcium regulated intracellular signals. Properties Chemical formula and molecular weight IP3 is an organic molecule with a molecular mass of 420.10 g/mol. Its empirical formula is C6H15O15P3. It is composed of an inositol ring with three phosphate groups bound at the 1, 4, and 5 carbon positions, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inward-rectifier Potassium Ion Channel
Inward-rectifier potassium channels (Kir, IRK) are a specific lipid-gated subset of potassium channels. To date, seven subfamilies have been identified in various mammalian cell types, plants, and bacteria. They are activated by phosphatidylinositol 4,5-bisphosphate ( PIP2). The malfunction of the channels has been implicated in several diseases. IRK channels possess a pore domain, homologous to that of voltage-gated ion channels, and flanking transmembrane segments (TMSs). They may exist in the membrane as homo- or heterooligomers and each monomer possesses between 2 and 4 TMSs. In terms of function, these proteins transport potassium (K+), with a greater tendency for K+ uptake than K+ export. The process of inward-rectification was discovered by Denis Noble in cardiac muscle cells in 1960s and by Richard Adrian and Alan Hodgkin in 1970 in skeletal muscle cells. Overview of inward rectification A channel that is "inwardly-rectifying" is one that passes current (positive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Growth Hormone-releasing Hormone
Growth may refer to: Biology * Auxology, the study of all aspects of human physical growth * Bacterial growth * Cell growth * Growth hormone, a peptide hormone that stimulates growth * Human development (biology) * Plant growth * Secondary growth, growth that thickens woody plants Economics * Economic growth, the increase in the inflation-adjusted market value of the goods and services * Growth investing, a style of investment strategy focused on capital appreciation Mathematics * Exponential growth, also called geometric growth * Hyperbolic growth * Linear growth, refers to two distinct but related notions * Logistic growth, characterized as an S curve Social science * Developmental psychology * Erikson's stages of psychosocial development * Human development (humanity) * Personal development * Population growth Other uses * ''Growth'' (film), a 2010 American horror film * Izaugsme (''Growth''), a Latvian political party * ''Grown'' (album), by 2PM See also * Grow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Channel
Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels and can be classified according to the trigger that opens the channel for such ions, i.e. either a voltage-change ("voltage-gated", "voltage-sensitive", or "voltage-dependent" sodium channel; also called "VGSCs" or "Nav channel") or a binding of a substance (a ligand) to the channel ( ligand-gated sodium channels). In excitable cells such as neurons, myocytes, and certain types of glia, sodium channels are responsible for the rising phase of action potentials. These channels go through three different states called resting, active and inactive states. Even though the resting and inactive states would not allow the ions to flow through the channels the difference exists with respect to their structural conformation. Selectivity Sodium channels are highly selective for the transport of ions across cell m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bruton's Tyrosine Kinase
Bruton's tyrosine kinase (abbreviated Btk or BTK), also known as tyrosine-protein kinase BTK, is a tyrosine kinase that is encoded by the ''BTK'' gene in humans. BTK plays a crucial role in B cell development. Structure BTK contains five different protein interaction domains. These domains include an amino terminal pleckstrin homology (PH) domain, a proline-rich TEC homology (TH) domain, SRC homology (SH) domains SH2 and SH3, as well as a kinase domain with enzymatic activity. Function BTK plays a crucial role in B cell development as it is required for transmitting signals from the pre-B cell receptor that forms after successful immunoglobulin heavy chain rearrangement. It also has a role in mast cell activation through the high-affinity IgE receptor. Btk contains a PH domain that binds phosphatidylinositol (3,4,5)-trisphosphate (PIP3). PIP3 binding induces Btk to phosphorylate phospholipase C, which in turn hydrolyzes PIP2, a phosphatidylinositol, into two second m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDPK1
In the field of biochemistry, PDPK1 refers to the protein 3-phosphoinositide-dependent protein kinase-1, an enzyme which is encoded by the ''PDPK1'' gene in humans. It is implicated in the development and progression of melanomas. Function PDPK1 is a master kinase, which is crucial for the activation of AKT/PKB and many other AGC kinases including PKC, S6K, SGK. An important role for PDPK1 is in the signalling pathways activated by several growth factors and hormones including insulin signaling. Mice lacking PDPK1 die during early embryonic development, indicating that this enzyme is critical for transmitting the growth-promoting signals necessary for normal mammalian development. Mice that are deficient in PDPK1 have a ≈40% decrease in body mass, mild glucose intolerance, and are resistant to cancer brought about by hyperactivation of the PI3K pathway (PTEN+/-). Plant PDK1 plays an important role in regulating PIN-mediated auxin transport, and is thus involved in v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class I PI 3-kinases
Class I PI 3-kinases are a subgroup of the enzyme family, phosphoinositide 3-kinase that possess a common protein domain structure, substrate specificity, and method of activation. Class I PI 3-kinases are further divided into two subclasses, class IA PI 3-kinases and class IB PI 3-kinases. Class IA PI 3-kinases Class IA PI 3-kinases are activated by receptor tyrosine kinases (RTKs). There are three catalytic subunits that are classified as class IA PI 3-kinases: *p110α * p110β *p110δ There are currently five regulatory subunits that are known to associate with class IA PI 3-kinases catalytic subunits: *p85α and p85β * p55α and p55γ * p50α Class IB PI 3-kinases Class IB PI 3-kinases are activated by G-protein-coupled receptors (GPCRs). The only known class IB PI 3-kinase catalytic subunit is p110γ. There are two known regulatory subunits for p110γ: * p101 *p84/ p87PIKAP. See also * Phosphoinositide 3-kinase#Class I * Phosphoinositide 3-kinase inhibitor Phosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
