Quantitative metabolomics services for biomarker discovery and validation.
Specializing in ready to use metabolomics kits.
Your source for quantitative metabolomics technologies and bioinformatics.

Filter by Pathway Type:



Showing 1 - 10 of 49833 pathways
SMPDB ID Pathway Chemical Compounds Proteins

SMP0000051

Pw000023 View Pathway
Metabolic

Fatty Acid Metabolism

Fatty acids constitute a large energy source for the body. The cellular membrane is also made up of fatty acids. During starvation times, fatty acids can provide energy to humans for numerous days. Fatty acid metabolism is also known as beta-oxidation. During metabolism, acetyl CoA is produced that can then enter the citric acid cycle. When ATP is needed, ATP may be generated by increasing fatty acid metabolism. Fatty acid metabolism is essentially the reverse reaction of fatty acid synthesis.

SMP0121012

Pw122279 View Pathway
Physiological

Kidney Function - Distal Convoluted Tubule

The distal convoluted tubule of the nephron is the part of the kidney between the loop of henle and the collecting duct. When renin is released from the kidneys, it causes the activation of angiotensin I in the blood circulation which is cleaved to become angiotensin II. Angiotensin II stimulates the release of aldosterone from the adrenal cortex and release of vasopressin from the posterior pituitary gland. When in the circulation, vasopressin eventually binds to receptors on epithelial cells in the distal convoluted tubule. This causes vesicles that contain aquaporins to fuse with the plasma membrane. Aquaporins are proteins that act as water channels once they have bound to the plasma membrane. As a result, the permeability of the distal convoluted tubule changes to allow for water reabsorption back into the blood circulation. In addition, sodium, chlorine, and calcium are also reabsorbed back into the systemic circulation via their respective channels and exchangers. However, aldosterone is a major regulator of the reabsorption of these ions as well, as it changes the permeability of the distal convoluted tubule to these ions. As a result, a high concentration of sodium, chlorine, and calcium in the blood vessels occurs. The reabsorption of ions and water increases blood fluid volume and blood pressure.

SMP0121128

Pw122406 View Pathway
Physiological

Pancreas Function - Delta Cell

Pancreatic delta cells produce somatostatin which functions to inhibit glucagon, insulin, and itself. Somatostatin is stored in granules in the delta cell and is released in response to an increase in blood sugar, calcium, and blood amino acids during absorption of a meal. In the process of somatostatin secretion, glucose must first undergo glycolysis in the mitochondrion to increase ATP in the cell. The inside of the alpha cell then becomes electrically positive due to the closure of potassium channels that were inhibited by ATP. From this closure, the potassium is no longer being shuttled out of the cell, thus depolarizing the cell due to the extra intracellular potassium. The resulting action potential from the increased membrane potential causes the voltage gate calcium channels to open, creating an influx of calcium into the cell. This triggers the exocytosis of somatostatin granules from the delta cell.

SMP0014212

Pw015076 View Pathway
Metabolic

Phosphatidylcholine Biosynthesis

Phosphatidylcholines (PC) are a class of phospholipids that incorporate a phosphocholine headgroup into a diacylglycerol backbone. They are the most abundant phospholipid in eukaryotic cell membranes and has both structural and signalling roles. In eukaryotes, there exist two phosphatidylcholine biosynthesis pathways: the Kennedy pathway and the methylation pathway. The Kennedy pathway begins with the direct phosphorylation of free choline into phosphocholine followed by conversion into CDP-choline and subsequently phosphatidylcholine. It is the major synthesis route in animals. The methylation pathway involves the 3 successive methylations of phosphatidylethanolamine to form phosphatidylcholine. The first reaction of the Kennedy pathway involves the cytosol-localized enzyme choline/ethanolamine kinase catalyzing the conversion of choline into phosphocholine. Second, choline-phosphate cytidylyltransferase, localized to the endoplasmic reticulum membrane, catalyzes the conversion of phosphocholine to CDP-choline. Last, choline/ethanolaminephosphotransferase catalyzes phosphatidylcholine biosynthesis from CDP-choline. It requires either magnesium or manganese ions as cofactors. A parallel Kennedy pathway forms phosphatidylethanolamine from ethanolamine - the only difference being a different enzyme, ethanolamine-phosphate cytidylyltransferase, catalyzing the second step. Phosphatidylethanolamine is also synthesized from phosphatidylserine in the mitochondrial membrane by phosphatidylserine decarboxylase. Phosphatidylethanolamine funnels into the methylation pathway in which phosphatidylethanolamine N-methyltransferase (PEMT) then catalyzes three sequential N-methylation steps to convert phosphatidylethanolamine to phosphatidylcholine. PEMT uses S-adenosyl-L-methionine as a methyl donor.

SMP0000716

Pw000693 View Pathway
Metabolic

Thyroid Hormone Synthesis

Thyroid hormone synthesis is a process that occurs in the thyroid gland in humans that results in the production of thyroid hormones which regulate many different processes in the body, such as metabolism, temperature regulation and growth/development. Thyroid hormone synthesis begins in the nucleus of a thyroid follicular cell, as thyroglobulin synthesis occurs here and is transported to the endoplasmic reticulum. From there, thyroglobulin transported through endocytosis into the intracellular space, and then transported through exocytosis to the follicle colloid. There, thyroglobulin is joined by iodide that has been transported from the blood, through the thyroid follicular cell and arrived in the the follicle colloid using pendrin, and hydrogen peroxide to be catalyzed by thyroid peroxidase, creating thyroglobulin + iodotyrosine. Then, iodide, hydrogen peroxide and thyroidperoxidase create thyroglobulin + 3,5-diiodo-L-tyrosine. Thyroglobulin+3,5-diiodo-L-tyrosine then joins with hydrogen peroxide and thyroid peroxidase to create thyroglobulin + 2-aminoacrylic acid and thyroglobulin+liothyronine. Thyroglobulin + liothyronine then goes through two processes, the first being its transportation into the cell and undergoing of proteolysis, which is followed by liothyronine being transported into the bloodstream. The second process is thyroglobulin + liothyronine being catalyzed by thyroid peroxidase and resulting in the production of thyroglobulin + thyroxine. Thyroglobulin + thyroxine is then transported back into the cell, undergoes proteolysis, and thyroxine alone is transported back out of the cell and into the bloodstream.

SMP0000015

Pw000004 View Pathway
Metabolic

Glutathione Metabolism

Glutathione (GSH) is an low-molecular-weight thiol and antioxidant in various species such as plants, mammals and microbes. Glutathione plays important roles in nutrient metabolism, gene expression, etc. and sufficient protein nutrition is important for maintenance of GSH homeostasis. Glutathione is synthesized from glutamate, cysteine, and glycine sequentially by gamma-glutamylcysteine synthetase and GSH synthetase. L-Glutamic acid and cysteine are synthesized to form gamma-glutamylcysteine by glutamate-cysteine ligase that is powered by ATP. Gamma-glutamylcysteine and glycine can be synthesized to form glutathione by enzyme glutathione synthetase that is powered by ATP, too. Glutathione exists oxidized (GSSG) states and in reduced (GSH) state. Oxidation of glutathione happens due to relatively high concentration of glutathione within cells.

SMP0000465

Pw000016 View Pathway
Metabolic

Carnitine Synthesis

Carnitine is an ammonium compound that exists in two stereoisomers, of which only L-carnitine is biologically active. Carnitine can be obtained from dietary sources and also biosynthesized. It is necessary for fatty acid oxidation, transporting fatty acids from the cystosol to the mitochondria, where they are broken down via the citric acid cycle to release energy. Carnitine is synthesized from lysine residues in existing proteins. These residues are methylated using lysine methyltransferase enzymes and methyl groups from S-adenosylmethionine, then removed from the protein via hydrolysis. In the next step, the N6,N6,N6-trimethyl-L-lysine is converted to 3-hydroxy-N6,N6,N6-trimethyl-L-lysine t via the mitochondrial enzyme trimethyllysine dioxygenase. The 3-hydroxy-N6,N6,N6-trimethyl-L-lysine is then cleaved to 4-trimethylammoniobutanal and glycine, likely by an aldose identical to serine hydroxymethyltransferase. Next, 4-trimethylammoniobutanal is oxidized by the 4-trimethylaminobutyraldehyde dehydrogenase protein to 4-trimethylammoniobutanoic acid. Finally, 4-trimethylammoniobutanoic acid is transformed into L-carnitine via the enzyme gamma-butyrobetaine dioxygenase. The reactions in the carnitine synthesis pathway occur ubiquitously in the human body with the exception of the last step, as the gamma-butyrobetaine dioxygenase enzyme is found only in the liver and kidney (and at very low levels in the brain). The produced carnitine is then carried to other tissue via a number of transport systems.

SMP0000060

Pw000054 View Pathway
Metabolic

Pyruvate Metabolism

Pyruvate is an intermediate compound in the metabolism of fats, proteins, and carbohydrates. It can be formed from glucose via glycolysis or the transamination of alanine. It can be converted into Acetyl-CoA to be used as the primary energy source for the TCA cycle, or converted into oxaloacetate to replenish TCA cycle intermediates. Pyruvate can also be used to synthesize carbohydrates, fatty acids, ketone bodies, alanine, and steroids. In conditions of inssuficient oxygen or in cells with few mitochondria, pyruvate is reduced to lactate in order to re-oxidize NADH back into NAD+ Pyruvate participates in several key reactions and pathways. In glycolysis, phosphoenolpyruvate (PEP) is converted to pyruvate by pyruvate kinase in an highly exergonic and irreversible reaction. In gluconeogenesis, pyruvate carboxylase and PEP carboxykinase are needed to catalyze the conversion of pyruvate to PEP. In fatty acid synthesis, the pyruvate dehydrogenase complex decarboxylates pyruvate to produce acetyl-CoA. In gluconeogenesis, the carboxylation by pyruvate carboxylase produces oxaloacetate. The fate of pyruvate depends on the cell energy charge. In cells or tissues with a high energy charge pyruvate is directed toward gluconeogenesis, but when the energy charge is low pyruvate is preferentially oxidized to CO2 and H2O in the TCA cycle, with generation of 15 equivalents of ATP per pyruvate. The enzymatic activities of the TCA cycle are located in the mitochondrion. When transported into the mitochondrion, pyruvate encounters two principal metabolizing enzymes: pyruvate carboxylase (a gluconeogenic enzyme) and pyruvate dehydrogenase (PDH). With a high cell-energy charge, acetyl-CoA, is able allosterically to activate pyruvate carboxylase, directing pyruvate toward gluconeogenesis. When the energy charge is low CoA is not acylated, pyruvate carboxylase is inactive, and pyruvate is preferentially metabolized via the PDH complex and the enzymes of the TCA cycle to CO2 and H2O.

SMP0030406

Pw031290 View Pathway
Metabolic

Androstenedione Metabolism

Androstenedione is an endogenous weak androgen steroid hormone that is a precursor of testosterone and other androgens, as well as of estrogens like estrone . Its metabolism occurs primarily in the endoplasmic reticulum (membrane-associated enzymes are coloured dark green in the image). Conversion of androstenedione to testosterone requires the enzyme testosterone 17-beta-dehydrogenase 3. Conversion of androstenedione to estrone involves three successive reactions catalyzed by the enzyme aromatase (cytochrome P450 19A1). Androstenedione can also be converted into etiocholanolone glucuronide, androsterone glucuronide, and adrenosterone. The three-reaction subpathway to synthesize etiocholanolone glucuronide begins with the enzyme 3-oxo-5-beta-steroid 4-dehydrogenase catalyzing the conversion of androstenedione to etiocholanedione. This is followed by the conversion of etiocholanedione to etiocholanolone which is catalyzed by aldo-keto reductase family 1 member C4. Lastly, the large membrane-associated multimer UDP-glucuronosyltransferase 1-1 catalyzes the conversion of etiocholanolone to etiocholanolone glucuronide. The three-reaction subpathway to synthesize androsterone glucuronide begins with the conversion of androstenedione to androstanedione via 3-oxo-5-alpha-steroid 4-dehydrogenase 1. Anstrostanedione is then converted into androsterone via aldo-keto reductase family 1 member C4. The last reaction to form androsterone glucuronide is catalyzed by the large multimer UDP-glucuronosyltransferase 1-1. The two-reaction subpathway to synthesize adrenosterone begins in the mitochondrial inner membrane where androstenedione is first converted into 11beta-hydroxyandrost-4-ene-3,17-dione by the enzyme cytochrome P450 11B1. Following transport to the endoplasmic reticulum, 11beta-hydroxyandrost-4-ene-3,17-dione is converted into adrenosterone via corticosteroid 11-beta-dehydrogenase isozyme 1.

SMP0000059

Pw000162 View Pathway
Metabolic

Urea Cycle

Urea, also known as carbamide, is a waste product made by a large variety of living organisms and is the main component of urine. Urea is created in the liver, through a string of reactions that are called the Urea Cycle. This cycle is also called the Ornithine Cycle, as well as the Krebs-Henseleit Cycle. There are some essential compounds required for the completion of this cycle, such as arginine, citrulline and ornithine. Arginine cleaves and creates urea and ornithine, and the reactions that follow see urea residue build up on ornithine, which recreates arginine and keeps the cycle going. Ornithine is transported to the mitochondrial matrix, and once there, ornithine carbamoyltransferase uses carbamoyl phosphate to create citrulline. After this, citrulline is transported to the cytosol. Once here, citrulline and aspartate team up to create argininosuccinic acid. After this, argininosuccinate lyase creates l-arginine. L-arginine finally uses arginase-1 to create ornithine again, which will be transported to the mitochondrial matrix and restart the urea cycle once more.
Showing 1 - 10 of 49833 pathways