|
Snf3
Snf3 is a protein which regulates glucose uptake in yeast. It senses glucose in the environment with high affinity. Introduction Glucose sensing and signaling in budding yeast is similar to the mammalian system in many ways. However, there are also significant differences. Mammalian cells regulate their glucose uptake via hormones (i.e. insulin and glucagon) or intermediary metabolites. In contrast, yeast as a unicellular organism does not depend on hormones but on nutrients in the medium. The presence of glucose induces a conformational change in the membrane proteins Snf3/Rgt2 or Gpr1, and regulates expression of genes involved in glucose metabolism. Homology and function Snf3 is homologous to multiple sugar transporters, it shares high similarity to the glucose transporters of rat brain cells and human HepG2 hepatoma cells, as well as to the arabinose and xylose transporters (AraE and XylE) of ''Escherichia coli''.Celenza JL, Marshall-Carlson L, Carlson M (1988). The yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snf3 Img1
Snf3 is a protein which regulates glucose uptake in yeast. It senses glucose in the environment with high affinity. Introduction Glucose sensing and signaling in budding yeast is similar to the mammalian system in many ways. However, there are also significant differences. Mammalian cells regulate their glucose uptake via hormones (i.e. insulin and glucagon) or intermediary metabolites. In contrast, yeast as a unicellular organism does not depend on hormones but on nutrients in the medium. The presence of glucose induces a conformational change in the membrane proteins Snf3/Rgt2 or Gpr1, and regulates expression of genes involved in glucose metabolism. Homology and function Snf3 is homologous to multiple sugar transporters, it shares high similarity to the glucose transporters of rat brain cells and human HepG2 hepatoma cells, as well as to the arabinose and xylose transporters (AraE and XylE) of '' Escherichia coli''.Celenza JL, Marshall-Carlson L, Carlson M (1988). Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snf3 Img2
Snf3 is a protein which regulates glucose uptake in yeast. It senses glucose in the environment with high affinity. Introduction Glucose sensing and signaling in budding yeast is similar to the mammalian system in many ways. However, there are also significant differences. Mammalian cells regulate their glucose uptake via hormones (i.e. insulin and glucagon) or intermediary metabolites. In contrast, yeast as a unicellular organism does not depend on hormones but on nutrients in the medium. The presence of glucose induces a conformational change in the membrane proteins Snf3/Rgt2 or Gpr1, and regulates expression of genes involved in glucose metabolism. Homology and function Snf3 is homologous to multiple sugar transporters, it shares high similarity to the glucose transporters of rat brain cells and human HepG2 hepatoma cells, as well as to the arabinose and xylose transporters (AraE and XylE) of ''Escherichia coli''.Celenza JL, Marshall-Carlson L, Carlson M (1988). The yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucose Transporter
Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane, a process known as facilitated diffusion. Because glucose is a vital source of energy for all life, these transporters are present in all phyla. The GLUT or SLC2A family are a protein family that is found in most mammalian cells. 14 GLUTS are encoded by human genome. GLUT is a type of uniporter transporter protein. Synthesis of free glucose Most non-autotrophic cells are unable to produce free glucose because they lack expression of glucose-6-phosphatase and, thus, are involved only in glucose uptake and catabolism. Usually produced only in hepatocytes, in fasting conditions, other tissues such as the intestines, muscles, brain, and kidneys are able to produce glucose following activation of gluconeogenesis. Glucose transport in yeast In ''Saccharomyces cerevisiae'' glucose transport takes place through facilitated diffusion. The transport ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmembrane Domain
A transmembrane domain (TMD) is a membrane-spanning protein domain. TMDs generally adopt an alpha helix topological conformation, although some TMDs such as those in porins can adopt a different conformation. Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in TMDs are often hydrophobic, although proteins such as membrane pumps and ion channels can contain polar residues. TMDs vary greatly in length, sequence, and hydrophobicity, adopting organelle-specific properties. Functions of transmembrane domains Transmembrane domains are known to perform a variety of functions. These include: * Anchoring transmembrane proteins to the membrane. *Facilitating molecular transport of molecules such as ions and proteins across biological membranes; usually hydrophilic residues and binding sites in the TMDs help in this process. *Signal transduction across the membrane; many transmembrane proteins, such as G protein-coupled receptors, receive extracel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Protein
Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane proteins are a permanent part of a cell membrane and can either penetrate the membrane ( transmembrane) or associate with one or the other side of a membrane ( integral monotopic). Peripheral membrane proteins are transiently associated with the cell membrane. Membrane proteins are common, and medically important—about a third of all human proteins are membrane proteins, and these are targets for more than half of all drugs. Nonetheless, compared to other classes of proteins, determining membrane protein structures remains a challenge in large part due to the difficulty in establishing experimental conditions that can preserve the correct conformation of the protein in isolation from its native environment. Function Membrane proteins perform a variety of functions vital to the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topology
In mathematics, topology (from the Greek words , and ) is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, without closing holes, opening holes, tearing, gluing, or passing through itself. A topological space is a set endowed with a structure, called a ''topology'', which allows defining continuous deformation of subspaces, and, more generally, all kinds of continuity. Euclidean spaces, and, more generally, metric spaces are examples of a topological space, as any distance or metric defines a topology. The deformations that are considered in topology are homeomorphisms and homotopies. A property that is invariant under such deformations is a topological property. Basic examples of topological properties are: the dimension, which allows distinguishing between a line and a surface; compactness, which allows distinguishing between a line and a circle; connectedne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ubiquitylation
Ubiquitin is a small (8.6 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e., it is found ''ubiquitously''. It was discovered in 1975 by Gideon Goldstein and further characterized throughout the late 1970s and 1980s. Four genes in the human genome code for ubiquitin: UBB, UBC, UBA52 and RPS27A. The addition of ubiquitin to a substrate protein is called ubiquitylation (or, alternatively, ubiquitination or ubiquitinylation). Ubiquitylation affects proteins in many ways: it can mark them for degradation via the proteasome, alter their cellular location, affect their activity, and promote or prevent protein interactions. Ubiquitylation involves three main steps: activation, conjugation, and ligation, performed by ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s), and ubiquitin ligases (E3s), respectively. The result of this sequential cascade is to bind ubiquitin to lysine residues on the protein substrate via an isopeptide bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SCF Complex
Skp, Cullin, F-box containing complex (or SCF complex) is a multi-protein E3 ubiquitin ligase complex that catalyzes the ubiquitination of proteins destined for 26S proteasomal degradation. Along with the anaphase-promoting complex, SCF has important roles in the ubiquitination of proteins involved in the cell cycle. The SCF complex also marks various other cellular proteins for destruction. Core components SCF contains a variable F-box protein and three core subunits: * F-box protein (FBP) – FBP contributes to the substrate specificity of the SCF complex by first aggregating to target proteins independently of the complex. Each FBP (e.g. Skp2) may recognize several different substrates in a manner that is dependent on post-translational modifications such as phosphorylation or glycosylation. FBP then binds to Skp1 of the SCF complex using an F-box motif, bringing the target protein into proximity with the functional E2 ubiquitin-conjugating enzyme. FBP is also essential in re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteasome
Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Enzymes that help such reactions are called proteases. Proteasomes are part of a major mechanism by which cells regulate the concentration of particular proteins and degrade misfolded proteins. Proteins are tagged for degradation with a small protein called ubiquitin. The tagging reaction is catalyzed by enzymes called ubiquitin ligases. Once a protein is tagged with a single ubiquitin molecule, this is a signal to other ligases to attach additional ubiquitin molecules. The result is a ''polyubiquitin chain'' that is bound by the proteasome, allowing it to degrade the tagged protein. The degradation process yields peptides of about seven to eight amino acids long, which can then be further degraded into shorter amino acid sequences and used in synthesizing new proteins. Proteasomes are found inside all eukaryotes and archaea, and in some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorylation
In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. Protein phosphorylation often activates (or deactivates) many enzymes. Glucose Phosphorylation of sugars is often the first stage in their catabolism. Phosphorylation allows cells to accumulate sugars because the phosphate group prevents the molecules from diffusing back across their transporter. Phosphorylation of glucose is a key reaction in sugar metabolism. The chemical equation for the conversion of D-glucose to D-glucose-6-phosphate in the first step of glycolysis is given by :D-glucose + ATP → D-glucose-6-phosphate + ADP :ΔG° = −16.7 kJ/mol (° indicates measurement at standard condition) Hepatic cells are freely permeable to glucose, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-terminus
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus. Chemistry Each amino acid has a carboxyl group and an amine group. Amino acids link to one another to form a chain by a dehydration reaction which joins the amine group of one amino acid to the carboxyl group of the next. Thus polypeptide chains have an end with an unbound carboxyl group, the C-terminus, and an end with an unbound amine group, the N-terminus. Proteins are naturally synthesized starting from the N-terminus and ending at the C-terminus. Function C-terminal retention signals While the N-terminus of a protein often co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinase
In biochemistry, a kinase () is an enzyme that catalysis, catalyzes the transfer of phosphate groups from High-energy phosphate, high-energy, phosphate-donating molecules to specific Substrate (biochemistry), substrates. This process is known as phosphorylation, where the high-energy adenosine triphosphate, ATP molecule donates a phosphate group to the substrate (biology), substrate molecule. This transesterification produces a phosphorylated substrate and Adenosine diphosphate, ADP. Conversely, it is referred to as dephosphorylation when the phosphorylated substrate donates a phosphate group and adenosine diphosphate, ADP gains a phosphate group (producing a dephosphorylated substrate and the high energy molecule of ATP). These two processes, phosphorylation and dephosphorylation, occur four times during glycolysis. Kinases are part of the larger family of phosphotransferases. Kinases should not be confused with phosphorylases, which catalyze the addition of inorganic phosphate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.png "Click for more on -> Transmembrane Domain")
