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Pathways  Metabolism

Metabolism  
Click To View Pathway ADP-Ribosylation Factor
ADP-ribosylation factors (ARFs) are 20-kDa guanine nucleotide-binding proteins, members of the Ras GTPase superfamily that were initially recognized and purified because of their ability to stimulate the ADP-ribosyltransferase activity of the cholera ...
Click To View Pathway Beta-Oxidation of Fatty Acids
Fatty acids provide highly efficient energy storage, storing much more energy for their weight than carbohydrates like glucose. Fatty acids are stored as triglycerides in adipose tissue, in which each triglyceride molecule contains three fatty acids ...
Click To View Pathway Biosynthesis of Arginine in Bacteria
Click To View Pathway Biosynthesis of Chorismate in Bacteria and Plants
The biosynthesis of all three aromatic amino acids (tryptophan, tyrosine and phenylalanine) begins with the metabolic intermediate chorismate. The biosynthesis of chorismate occurs only in plants and bacterial, not in animals. The first step in the p ...
Click To View Pathway Biosynthesis of Cysteine from serine in bacteria and plants
In animals cysteine is synthesized from homocysteine, a produce of the essential amino acid methionine. In the absence of dietary methionine, animals cannot make cysteine. Bacteria and plants however produce cysteine by a different biosynthetic rou ...
Click To View Pathway Biosynthesis of Cysteine in mammals
In animals, the sulfur-containing amino acid cysteine is synthesized from homocysteine, which is itself derived from metabolism of the amino acid methionine. Methionine is an essential amino acid for animals, making cysteine indirectly an essential ...
Click To View Pathway Biosynthesis of Glycine and Serine
Intermediates in energy production pathways such as glycolysis and the Kreb's cycle are commonly the starting point for the biosynthesis of amino acids. The glycolytic intermediate 3-phosphoglycerate is the starting point for the biosynthesis of ser ...
Click To View Pathway Biosynthesis of Histidine
Click To View Pathway Biosynthesis of isoleucine
Isoleucine is an essential amino acid, only synthesized in plants and bacteria, and required in the diet by animals. In proteins, the hydrophobic isoleucine side-chain tends to reside with other hydrophobic residues in the interior of globular protei ...
Click To View Pathway Biosynthesis of leucine
Click To View Pathway Biosynthesis of Lysine
Click To View Pathway Biosynthesis of neurotransmitters
Neurotransmitters are signaling molecules used by neurons to communicate across chemical synapses. The receptors for neurotransmitters include G-protein coupled receptors (GPCRs) and ligand-gated ion channels. The biogenic amines are neurotransmitter ...
Click To View Pathway Biosynthesis of phenylalanine and tyrosine in bacteria and plants
Click To View Pathway Biosynthesis of Proline in Bacteria
Among the twenty amino acids encoded by the genetic code, proline is unique in having a cyclic structure with its side chain connected to the amino group to create a secondary amine. As a consequence of its cyclic structure, proline constrains the st ...
Click To View Pathway Biosynthesis of spermidine and spermine
The polyamines spermidine and spermine are expressed in a variety of tissues and are involved in the regulation of apoptosis, cellular proliferation, and progression through the cell cycle. Depletion of polyamines appears to reduce cell growth, and i ...
Click To View Pathway Biosynthesis of sphingolipids
Click To View Pathway Biosynthesis of threonine and methionine
Click To View Pathway Biosynthesis of Tryptophan in Bacteria and Plants
The aromatic amino acid tryptophan is an essential nutrient, meaning that humans and animals do not themselves have the biosynthetic machinery to synthesize tryptophan but rely on dietary intake from bacteria and plants that do produce it. Tryptophan ...
Click To View Pathway Biosynthesis of valine
Click To View Pathway Catabolic pathway for asparagine and asparate
Aspartate and asparagine are catabolized into oxaloacetate and the Kreb's cycle in a fairly direct pathway for amino acids with four carbons. The first step for asparagine catabolism is hydrolysis by the enzyme asparaginase, releasing aspartate and ...
Click To View Pathway Catabolic pathways for alanine, glycine, serine, cysteine, tryptophan, and threonine
Amino acids in the diet have one of two fates - either they are incorporated into proteins or they are broken down for energy and metabolic intermediates. They are not stored and the body also does not excrete them intact. The metabolic pathways that ...
Click To View Pathway Catabolic Pathways for Arginine , Histidine, Glutamate, Glutamine, and Proline
Glutamine is converted to glutamate by glutaminase or several other enzymes by the removal of the amide nitrogen. Proline is first converted to a Schiff base and then converted by hydrolysis to glutamate-5-semialdehyde. All of these changes occur o ...
Click To View Pathway Catabolic Pathways for Methionine, Isoleucine, Threonine and Valine
The carbon chains of methionine, isoleucine, threonine and valine are broken down to produce succinyl-CoA, which feeds into the Citric Acid Cycle. Methionine donates its methyl group via S-adenosylmethionine to one of several acceptors and the four ...
Click To View Pathway ChREBP regulation by carbohydrates and cAMP
Although insulin and glucagon play important roles in regulating the response of cells to nutrients, cells also respond to carbohydrates through transcriptional regulation by the glucose responsive transcription factor ChREBP. ChREBP, carbohydrate r ...
Click To View Pathway Comparison of Beta oxidation in mitochondria and peroxisomes and glyoxysomes
In addition to the beta-oxidation of fatty acids in mitochondria, animal cells carry out beta-oxidation in another organelle, the peroxisome. Although the mitochondrial and peroxisomal beta-oxidation pathways are similar, the details differ somewhat ...
Click To View Pathway De novo synthesis of pyrimidine nucleotides
The pyrimidine ribonucleotides, those found in RNA, are uracil and cytosine, each containing the sugar ribose and a nitrogenous base. Pyrimidine nucleotides contain a single ring in the nitrogenous base. In contrast to the synthesis of purines, the ...
Click To View Pathway Eicosanoid Metabolism
The eicosanoids are a family of lipophilic hormones derived from the twenty carbon fatty acid arachidonic acid. Although they are diverse in structure, many eicosanoids have roles in inflammation, including regulation of vasodilation, vascular perme ...
Click To View Pathway Electron Transport Reaction in Mitochondria
The body gets energy through the oxidation of food such as glucose and fatty acids. The chemical energy contained in these foods is extracted and converted until it reaches a common form, the high-energy phosphate bonds of ATP. The hydrolysis of AT ...
Click To View Pathway ER–associated degradation (ERAD) Pathway
The endoplasmic reticulum (ER) of the cell operates a quality control system that identifies misfolded proteins, transports them into the cytoplasm and then targets them for degradation by the proteasome. Aberrant protein degradation is the mechanism ...
Click To View Pathway Extrinsic Prothrombin Activation Pathway
Blood coagulation or clotting takes place in 3 essential phases. The first phase is the activation of a prothrombin activator complex. The second phase is the activation of prothrombin. The third stage is clot formation as a result of fibrinogen c ...
Click To View Pathway Feeder Pathways for Glycolysis
The glycolytic pathway begins with the simple sugar glucose and leads to pyruvate and eventually the Kreb's cycle. Dietary carbohydrates include a variety of sugars that are funneled into glycolysis to supply energy, including other monosaccharides, ...
Click To View Pathway Fibrinolysis Pathway
Clot formation and fibrinolysis is a balance of plasmin activation/inhibition and thrombin-thrombomodulin activity that regulates fibrin polymer formation and degradation. Active thrombin is produced by the cleavage of prothrombin in the
Click To View Pathway Formation of Ketone Bodies from acetyl-CoA
The acetyl-CoA produced by mitochondrial beta-oxidation of fatty acids enters the Kreb's cycle to produce energy, but that is not the only fate of acetyl-CoA. In liver mitochondria, some acetyl-CoA is converted to acetoacetate, beta-hydroxybutyrate, ...
Click To View Pathway Formation of Phagosomes and Recruitment of Endoplasmic Reticulum
Mammalian cells take up extracellular material by a variety of different mechanisms that are collectively termed endocytosis. Endocytic mechanisms serve many important cellular functions including the uptake of extracellular nutrients, regulation of ...
Click To View Pathway Free Radical Induced Apoptosis
Oxidative stress is one factor that can trigger programmed cell death. Activated neutrophils responding to inflammatory stimulation produce reactive oxygen species like superoxide free radicals to kill invading bacteria, but these reactive oxygen spe ...
Click To View Pathway FXR and LXR Regulation of Cholesterol Metabolism
Cholesterol is essential for life and a key in the development of heart disease. Cholesterol homeostasis is achieved through regulation of cholesterol uptake, cholesterol biosynthesis, cholesterol conversion to bile acids and excretion of bile acids. ...
Click To View Pathway Ghrelin: Regulation of Food Intake and Energy Homeostasis
The somatotropic axis. The synthesis and release of growth hormone (GH) from the pituitary are controlled by the hypothalamic hormones GH-releasing hormone (GHRH) and somatostatin (SRIF), which in turn are regulated by feedback (dashed lines) from bl ...
Click To View Pathway Glucogenic and Ketogenic Amino Acids
A significant amount of metabolic energy can come from amino acid metabolism, particularly under conditions of starvation. The metabolism of amino acids occurs through common metabolic intermediates, many of them part of or linked to the Krebs cycle ...
Click To View Pathway Glycolysis Pathway
Glycolysis was one of the first metabolic pathways studied and is one of the best understood, in terms of the enzymes involved, their mechanisms of action, and the regulation of the pathway to meet the needs of the organism and the cell. The glycolyt ...
Click To View Pathway Intrinsic Prothrombin Activation Pathway
Blood coagulation or clotting takes place in 3 essential phases. The first phase is the activation of a prothrombin activator complex. The second phase is the activation of prothrombin. The third stage is clot formation as a result of fibrinogen c ...
Click To View Pathway Lactose Synthesis
The synthesis of glycosidic bonds between monosaccharides requires energy input, energy that is provided by joining sugar monomers to a nucleotide such as UDP. Glycosyl transferases join two sugar monomers together, with UDP as the leaving group tha ...
Click To View Pathway Leloir pathway of galactose metabolism
Galactose is a hexose sugar found in the disaccharide lactose. Galactose has six carbons like glucose and differs from glucose only in the stereochemistry of one carbon, C4. The enzymes of carbohydrate metabolism are specific enough that galactose ...
Click To View Pathway Low-density lipoprotein (LDL) pathway during atherogenesis
Low-density lipoprotein (LDL) is a plasma lipoprotein particle whose lipid component includes cholesterol and triglycerides and is commonly referred to as “bad cholesterol” due to its role promoting atherogenic heart disease. LDL in the plasma origi ...
Click To View Pathway Malate-aspartate shuttle
Most of the energy derived from the oxidation of glucose is not extracted directly as ATP, but as reduced NADH that transfers high-energy electrons to the electron transport chain in the inner mitochondrial membrane. This NADH comes primarily from t ...
Click To View Pathway Mechanism of Acetaminophen Activity and Toxicity
Acetaminophen is one of the worlds most commonly used drugs, used for the treatment of pain and fever. Like other NSAIDs (non-steroidal anti-inflammatory drugs), acetaminophen has a unique activity profile based in part on its action at its molecula ...
Click To View Pathway Mechanism of Protein Import into the Nucleus
Nuclear pore complexes (NPCs) are large proteinaceous assemblies that provide the only known portals for exchanging macromolecules between the nucleus and cytoplasm. This includes the movement of small molecules and the selective, facilitated transpo ...
Click To View Pathway Metabolism of Anandamide, an Endogenous Cannabinoid
The lipid anandamide derived from arachidonic acid binds to the cannabinoid G-protein coupled receptors CB-1 and CB-2 to exert its biological effects. The CB-1 receptor is also the site of action of the psychoactive components of marijuana, includin ...
Click To View Pathway Mitochondrial Carnitine Palmitoyltransferase (CPT) System
The oxidation of fatty acids is an important source of energy for ATP production in mitochondria through the entry of acetyl-CoA into the Krebs cycle. Fatty acids are oxidized inside the mitochondrial matrix but the fatty acids to be oxidized come fr ...
Click To View Pathway Multi-Drug Resistance Factors
Cancer cells resistant to a diverse set of hydrophobic drugs are known as MDR cells (multidrug-resistant). Large membrane proteins overproduced in MDR cells, belong to a family of transport P-glycoproteins known as ATP-binding cassette transporter p ...
Click To View Pathway Omega Oxidation
While the main route of fatty acid metabolism is through beta-oxidation, some minor metabolic pathways such as omega oxidation also contribute to the metabolism of fatty acids and other molecules. Omega oxidation occurs in the endoplasmic reticulum r ...
Click To View Pathway Oxidation of odd-numbered chain fatty acid, from Propionyl-CoA to Succinyl-CoA
The beta-oxidation of fatty acids in mitochondria progressively shortens fatty acids two-carbons at a time as acetyl-CoA units are removed with each round of the cycle. Fatty acids that enter beta-oxidation with an even number of carbons are converte ...
Click To View Pathway Oxidation of Polyunsaturated Fatty Acid
Unsaturated fatty acids are those that contain one or more double bonds in their alkyl-chain. Polyunsaturated fats with two double bonds usually have one between carbons 9 and 10 in the alkyl chain and another three carbons away (carbons 12-13). The ...
Click To View Pathway Oxidative reactions of the pentose phosphate pathway
One form of chemical energy used to drive biosynthetic reactions forward is the reducing power of the energy carrier NADPH. NADPH is essential to drive the biosynthesis of fatty acids and cholesterol for example. While NADPH is an important energy ...
Click To View Pathway Phosphatidylcholine Biosynthesis Pathway
The main components of biological membranes are phosphoglyceride lipids composed of a glycerol unit esterified to two fatty acids and a polar alcohol group. The properties of phospholipids give lipid bilayer membranes their self-organizing structure. ...
Click To View Pathway Phospholipid Biosynthesis in E. Coli Pathway
The biosynthesis of membrane phospholipids occurs through distinct pathways in mammals and bacteria. In the mammalian pathway for the synthesis of phosphatidylethanolamine, ethanolamine is first phosphorylated, activated to form CDP-ethanolamine and ...
Click To View Pathway Platelet Amyloid Precursor Protein Pathway
The amyloid -beta peptide (Ab), a proteolytic fragment of amyloid precursor protein (APP), is the major componenet of senile plaques, the hallmark of alzhemier’s disease. Platelets contain both APP and Ab and probably contribute greater than 90% of ...
Click To View Pathway Proteasome Complex
Attachment of the ubiquitin peptide to proteins targets them for proteolytic degradation by a complex cellular structure, the proteasome. The regulated proteolysis of proteins by proteasomes removes denatured, damaged or improperly translated protein ...
Click To View Pathway Rab GTPases Mark Targets In The Endocytotic Machinery
The eukaryotic cell contains compartments with distinct functions bounded by lipid bilayer membranes. The movement of membrane vesicles between these compartments allows proteins in the secretory pathway to move outward from the endoplasmic reticulu ...
Click To View Pathway Shuttle for transfer of acetyl groups from mitochondria to the cytosol
Acetyl-CoA is produced in mitochondria through the metabolism of fatty acids and the oxidation of pyruvate to acetyl-CoA. When ATP is needed, this acetyl-CoA can enter the Krebs cycle to drive oxidative phosphorylation. When ATP supplies are abunda ...
Click To View Pathway SREBP control of lipid synthesis
Sterol-regulatory element binding proteins (SREBPs) play a key role in transcriptional regulation of cholesterol metabolism in response to cholesterol levels in the cell. When cholesterol is abundant in the cell, the SREBPs are retained in the ER. ...
Click To View Pathway Starch Synthesis
The primary carbohydrate used for energy storage in plants is starch, the equivalent of glycogen in animals. Both starch and glycogen are polymers of glucose, with different glycosidic linkages between glucose monomers and different degrees of branc ...
Click To View Pathway Steps in the Glycosylation of Mammalian N-linked Oligosaccarides
The biosynthesis pathway of N-glycans is a costly system with respect to the number of enzymes that are involved in the synthesis and trimming of N-glycans. While the structural diversity of N-glycans in mature proteins in the cell surface is introdu ...
Click To View Pathway Sucrose Synthesis
The prodution of sucrose takes place in plants, to store energy produced during photosynthesis. The extraction of sucrose from plants like sugar cane and sugar beets is used to produce sugar for consumption, making this pathway of significant econom ...
Click To View Pathway Synthesis of Cardiolipin & phosphatidylinositol
Phosphoglycerides are lipids that contain glycerol with a phosphate ester on one end and two fatty acid ester side chains. Phosphoglycerides such as phosphatidylethanolamine and phosphatidylserine are the major component of lipid bilayer membranes ...
Click To View Pathway Synthesis of plasmalogens
Plasmalogens are a class of glycerophospholipids that contain one vinyl-ester linked long chain alcohol group in place of one ester-linked fatty acid chain found in other glycerophospholipids. As with the common glycerophospholipids, the polar head ...
Click To View Pathway Synthesis of Vitamin C
Click To View Pathway The Citric Acid Cycle
The Krebs cycle, also called the citric acid cycle, is a fundamental metabolic pathway involving eight enzymes essential for energy production through aerobic respiration, and, like glycolysis, arose early in evolution. This pathway is also an import ...
Click To View Pathway The IGF-1 Receptor and Longevity
A demonstrated means to increase lifespan in a wide range of organisms is through the restriction of caloric intake. Reducing the consumption of calories increases the lifespan of many different organisms, including mice. Although caloric restricti ...
Click To View Pathway The reactions that feed amino groups into the urea cycle
Excess amino acids in the body can be used as a source of energy, with their carbon skeleton converted to metabolic intermediates such as acetyl-CoA or intermediates in the Krebs cycle. The metabolic breakdown of amino acids releases nitrogen that m ...
Click To View Pathway The role of FYVE-finger proteins in vesicle transport
Eukaryotic cells take up constituents of the extra-cellular environment and regulate the cell-surface level of membrane proteins via a recycling system of membrane vesicles called endosomes. When cells are taking up elements from the cell-surface it ...
Click To View Pathway The salvage pathway from serine to phosphatidylcholine
The biosynthesis of membrane phospholipids occurs through distinct pathways in mammals and bacteria. In the mammalian pathway for the synthesis of phosphatidylethanolamine, ethanolamine is first phosphorylated, activated to form CDP-ethanolamine and ...
Click To View Pathway Visceral Fat Deposits and the Metabolic Syndrome
Obesity is associated with many adverse health effects, including an increased risk of diabetes and heart disease. The combined condition of obesity, diabetes and heart disease is sometimes referred to as the metabolic syndrome. One of the factors ...
Click To View Pathway Vitamin C in the Brain
Vitamin C (ascorbic acid) was first identified by virtue of the essential role it plays in collagen modification, preventing the nutritional deficiency scurvy. Vitamin C acts as a cofactor for hydroxylase enzymes that post-translationally modify col ...
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