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Ste5
Ste5 is a MAPK scaffold protein involved in the mating of yeast. The active complex is formed by interactions with the MAPK Fus3, the MAPK kinase (MAPKK) Ste7, and the MAPKK kinase Ste11. After the induction of mating by an appropriate mating pheromone (either a-factor or α –factor) Ste5 and its associated proteins are recruited to the membrane. Ste4 helps to recruit Ste5, Ste4 is not required for the attachment of Ste5 to the membrane. Membrane association depends on a pleckstrin homology domain, as well as an amphipathic An amphiphile (from the Greek αμφις amphis, both, and φιλíα philia, love, friendship), or amphipath, is a chemical compound possessing both hydrophilic (''water-loving'', polar) and lipophilic (''fat-loving'') properties. Such a compoun ... alpha-helical domain in the amino terminus. During mating, Fus3 MAPK and Ptc1 phosphatase compete to control 4 phosphorylation sites on the Ste5 scaffold. When all of 4 sites have been dephosphorylated by P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ste5 Protein Structure
Ste5 is a Mitogen-activated protein kinases, MAPK scaffold protein involved in the mating of yeast. The active complex is formed by interactions with the MAPK Fus3, the Mitogen-activated protein kinase kinase, MAPK kinase (MAPKK) Ste7, and the MAP kinase kinase kinase, MAPKK kinase Ste11. After the induction of mating by an appropriate mating pheromone (either a-factor or α –factor) Ste5 and its associated proteins are recruited to the Cell Membrane, membrane. Ste4 helps to recruit Ste5, Ste4 is not required for the attachment of Ste5 to the membrane. Membrane association depends on a pleckstrin homology domain, as well as an Amphiphile, amphipathic alpha-helical domain in the amino terminus. During mating, Fus3 MAPK and Ptc1 phosphatase compete to control 4 phosphorylation sites on the Ste5 scaffold. When all of 4 sites have been dephosphorylated by Ptc1, Fus3 is released and becomes active. Ste5 plays 2 main roles in the mating signal pathway: #Binds the components of the MAP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fus3
Fus3 is a MAPK protein involved in the mating decision of yeast. The dissociation of Fus3 from scaffold protein Ste5 results in the switch-like mating decision observed in yeast. During this process, Fus3 competes with a phosphatase Ptc1, attempting to phosphorylate 4 key phosphorylation sites on Ste5. When all 4 sites on Ste5 have been dephosphorylated by Ptc1, Fus3 dissociates from Ste5 and trans locates to the nucleus. One regulator of Fus3 is Ste5. Ste5 causes autophosphorylation of one of two locations modulated by the MAPK kinase Ste7 (the main activator of Fus3). This single phosphorylation causes Fus3 to phosphorylate Ste5 leading to a decrease in signal. However, Ste5 also selectively catalytically unlocks Fus3 for phosphorylation by Ste7. Both the catalytic domain on Ste5 as well as Ste7 must be present in order to activate Fus3, which helps to explain why Fus3 is only activated during the mating pathway, and remains inactive in other situations which use Ste7. When ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mating Of Yeast
The yeast ''Saccharomyces cerevisiae'' is a simple microorganism, single-celled eukaryote with both a diploid and haploid mode of existence. The mating of yeast only occurs between haploids, which can be either the a or α (alpha) mating type and thus display simple sexual differentiation. Mating type is determined by a single locus (genetics), locus, ''MAT'', which in turn governs the sexual behaviour of both haploid and diploid cells. Through a form of genetic recombination, haploid yeast can switch mating type as often as every cell cycle. Mating type and the life cycle of ''Saccharomyces cerevisiae'' ''S. cerevisiae'' (yeast) can stably exist as either a diploid or a haploid. Both haploid and diploid yeast cells reproduce by mitosis, with daughter cells budding off of mother cells. Haploid cells are capable of mating with other haploid cells of the opposite mating type (an a cell can only mate with an α cell, and vice versa) to produce a stable diploid cell. Diploid cells, usu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitogen-activated Protein Kinases
A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of protein kinase that is specific to the amino acids serine and threonine (i.e., a serine/threonine-specific protein kinase). MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines. They regulate cell functions including proliferation, gene expression, differentiation, mitosis, cell survival, and apoptosis. MAP kinases are found in eukaryotes only, but they are fairly diverse and encountered in all animals, fungi and plants, and even in an array of unicellular eukaryotes. MAPKs belong to the CMGC (CDK/MAPK/GSK3/CLK) kinase group. The closest relatives of MAPKs are the cyclin-dependent kinases (CDKs). Discovery The first mitogen-activated protein kinase to be discovered was ERK1 (MAPK3) in mammals. Since ERK1 and its close relative ERK2 (MAPK1) are both involved in growth factor signaling, the family was term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scaffold Protein
In biology, scaffold proteins are crucial regulators of many key signalling pathways. Although scaffolds are not strictly defined in function, they are known to interact and/or bind with multiple members of a signalling pathway, tethering them into complexes. In such pathways, they regulate signal transduction and help localize pathway components (organized in complexes) to specific areas of the cell such as the plasma membrane, the cytoplasm, the nucleus, the Golgi, endosomes, and the mitochondria. History The first signaling scaffold protein discovered was the Ste5 protein from the yeast ''Saccharomyces cerevisiae''. Three distinct domains of Ste5 were shown to associate with the protein kinases Ste11, Ste7, and Fus3 to form a multikinase complex. Function Scaffold proteins act in at least four ways: tethering signaling components, localizing these components to specific areas of the cell, regulating signal transduction by coordinating positive and negative feedback s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptc1
Ptc1 is a type Two C phosphatase involved in the mating decision of yeast. Ptc1 competes with Fus3 for control of the 4 phosphorylation sites on the scaffold protein Ste5. Presence of the mating pheromone α-factor causes Ptc1 to be recruited to Ste5. This recruitment takes place via a 4 amino acid motif in the Ste5 phosphosites. Ptc1 is also involved in regulating the osmotic stress of yeast, especially via inactivation of Hog1, a member of the MAPK A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of protein kinase that is specific to the amino acids serine and threonine (i.e., a serine/threonine-specific protein kinase). MAPKs are involved in directing cellular responses to ... pathway. This inactivation occurred as a result of dephosphorylation of the phosphotheronine but not the phosphotyrosine residue in the phosphorylation lip of Hog1.{{cite journal , last=Warmka , first=Janel , date=Jan 2001 , title= Ptc1, a Type 2C Ser/Thr Phosphatase, Inactivates the HO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitogen-activated Protein Kinase Kinase
Mitogen-activated protein kinase kinase (also known as MAP2K, MEK, MAPKK) is a dual-specificity kinase enzyme which phosphorylates mitogen-activated protein kinase (MAPK). MAP2K is classified as . There are seven genes: * (a.k.a. MEK1) * (a.k.a. MEK2) * (a.k.a. MKK3) * (a.k.a. MKK4) * (a.k.a. MKK5) * (a.k.a. MKK6) * (a.k.a. MKK7) The activators of p38 (MKK3 and MKK6), JNK (MKK4 and MKK7), and ERK (MEK1 and MEK2) define independent MAP kinase signal transduction pathways. The acronym MEK derives from MAPK/ERK Kinase. Role in melanoma MEK is a member of the MAPK signaling cascade that is activated in melanoma. When MEK is inhibited, cell proliferation is blocked and apoptosis (controlled cell death) is induced. See also * Signal transduction * MAP kinase * MAP kinase kinase kinase * MAP kinase kinase kinase kinase Mitogen-activated protein kinase kinase kinase kinase (MAP4K) is a family of proteins involved in cellular signal transduction. * MAP4K1 (aka HPK1) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MAP Kinase Kinase Kinase
Mitogen Activated Protein (MAP) kinase kinase kinase, MAPKKK (or MAP3K) is a serine/threonine-specific protein kinase which acts upon MAP kinase kinase. Subsequently, MAP kinase kinase activates MAP kinase. Several types of MAPKKK can exist but are mainly characterized by the MAP kinases they activate. MAPKKKs are stimulated by a large range of stimuli, primarily environmental and intracellular stressors. MAPKKK is responsible for various cell functions such as cell proliferation, cell differentiation, and apoptosis. The duration and intensity of signals determine which pathway ensues. Additionally, the use of protein scaffolds helps to place the MAPKKK in close proximity with its substrate to allow for a reaction. Lastly, because MAPKKK is involved in a series of several pathways, it has been used as a therapeutic target for cancer, amyloidosis, and neurodegenerative diseases. In humans, there are at least 19 genes which encode MAP kinase kinase kinases: * MAP3K1 (aka MEKK1) * M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pheromone
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavior of the receiving individuals. There are ''alarm signal, alarm pheromones'', ''food trail pheromones'', ''sex pheromones'', and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology. Background The portmanteau word "pheromone" was coined by Peter Karlson and Martin Lüscher in 1959, based on the Greek φερω ''pheroo'' ('I carry') and ὁρμων ''hormon'' ('stimulating'). P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of cells and organelles, being selectively permeable to ions a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleckstrin Homology Domain
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 p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphiphile
An amphiphile (from the Greek αμφις amphis, both, and φιλíα philia, love, friendship), or amphipath, is a chemical compound possessing both hydrophilic (''water-loving'', polar) and lipophilic (''fat-loving'') properties. Such a compound is called amphiphilic or amphipathic. Common amphiphilic substances are soaps, detergents, and lipoproteins. The phospholipid amphiphiles are the major structural component of cell membranes. Amphiphiles are the basis for a number of areas of research in chemistry and biochemistry, notably that of lipid polymorphism. Organic compounds containing hydrophilic groups at both ends of the molecule are called bolaamphiphilic. The micelles they form in the aggregate are prolate. Structure The lipophilic group is typically a large hydrocarbon moiety, such as a long chain of the form CH3(CH2)n, with n > 4. The hydrophilic group falls into one of the following categories: # charged groups #* anionic. Examples, with the lipophilic part of the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
