Phosphorylases
A class of glucosyltransferases that catalyzes the degradation of storage polysaccharides, such as glucose polymers, by phosphorolysis in animals (GLYCOGEN PHOSPHORYLASE) and in plants (STARCH PHOSPHORYLASE).
Glycogen Phosphorylase
An enzyme that catalyzes the degradation of GLYCOGEN in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. This enzyme exists in two forms: an active phosphorylated form ( PHOSPHORYLASE A) and an inactive un-phosphorylated form (PHOSPHORYLASE B). Both a and b forms of phosphorylase exist as homodimers. In mammals, the major isozymes of glycogen phosphorylase are found in muscle, liver and brain tissue.
Glycogen
Phosphorylase b
The inactive form of GLYCOGEN PHOSPHORYLASE that is converted to the active form PHOSPHORYLASE A via phosphorylation by PHOSPHORYLASE KINASE and ATP.
Glycogen Phosphorylase, Muscle Form
An isoenzyme of GLYCOGEN PHOSPHORYLASE that catalyzes the degradation of GLYCOGEN in muscle. Mutation of the gene coding this enzyme is the cause of McArdle disease (GLYCOGEN STORAGE DISEASE TYPE V).
Glycogen Phosphorylase, Liver Form
An isoenzyme of GLYCOGEN PHOSPHORYLASE that catalyzes the degradation of GLYCOGEN in liver tissue. Mutation of the gene coding this enzyme on chromosome 14 is the cause of GLYCOGEN STORAGE DISEASE TYPE VI.
Phosphorylase a
The active form of GLYCOGEN PHOSPHORYLASE that is derived from the phosphorylation of PHOSPHORYLASE B. Phosphorylase a is deactivated via hydrolysis of phosphoserine by PHOSPHORYLASE PHOSPHATASE to form PHOSPHORYLASE B.
Phosphorylase Kinase
Glycogen Synthase
Glycogen Phosphorylase, Brain Form
An isoenzyme of GLYCOGEN PHOSPHORYLASE that catalyzes the degradation of GLYCOGEN in brain tissue.
Liver Glycogen
Glycogen stored in the liver. (Dorland, 28th ed)
Purine-Nucleoside Phosphorylase
Uridine Phosphorylase
Adenosine Monophosphate
Glucosephosphates
'Glucosephosphates' are organic compounds resulting from the reaction of glucose with phosphoric acid, playing crucial roles in various metabolic processes, such as energy transfer and storage within cells.
Thymidine Phosphorylase
Phosphorylase Phosphatase
An enzyme that deactivates glycogen phosphorylase a by releasing inorganic phosphate and phosphorylase b, the inactive form. EC 3.1.3.17.
Glycogen Storage Disease Type VI
A hepatic GLYCOGEN STORAGE DISEASE in which there is an apparent deficiency of hepatic phosphorylase (GLYCOGEN PHOSPHORYLASE, LIVER FORM) activity.
Glycogen Storage Disease
Glucose-6-Phosphate
Glycogen Synthase Kinase 3
A glycogen synthase kinase that was originally described as a key enzyme involved in glycogen metabolism. It regulates a diverse array of functions such as CELL DIVISION, microtubule function and APOPTOSIS.
Glycogen Storage Disease Type V
Liver
Rabbits
Pyridoxal Phosphate
This is the active form of VITAMIN B 6 serving as a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into pyridoxamine phosphate (PYRIDOXAMINE).
Glucose
Glycogenolysis
The release of GLUCOSE from GLYCOGEN by GLYCOGEN PHOSPHORYLASE (phosphorolysis). The released glucose-1-phosphate is then converted to GLUCOSE-6-PHOSPHATE by PHOSPHOGLUCOMUTASE before entering GLYCOLYSIS. Glycogenolysis is stimulated by GLUCAGON or EPINEPHRINE via the activation of PHOSPHORYLASE KINASE.
Polyribonucleotide Nucleotidyltransferase
Enzyme Activation
Glucosyltransferases
Pyrimidine Phosphorylases
Glycogen Debranching Enzyme System
1,4-alpha-D-Glucan-1,4-alpha-D-glucan 4-alpha-D-glucosyltransferase/dextrin 6 alpha-D-glucanohydrolase. An enzyme system having both 4-alpha-glucanotransferase (EC 2.4.1.25) and amylo-1,6-glucosidase (EC 3.2.1.33) activities. As a transferase it transfers a segment of a 1,4-alpha-D-glucan to a new 4-position in an acceptor, which may be glucose or another 1,4-alpha-D-glucan. As a glucosidase it catalyzes the endohydrolysis of 1,6-alpha-D-glucoside linkages at points of branching in chains of 1,4-linked alpha-D-glucose residues. Amylo-1,6-glucosidase activity is deficient in glycogen storage disease type III.
Sugar Alcohols
Glycogen Synthase Kinases
A class of protein-serine-threonine kinases that was originally found as one of the three types of kinases that phosphorylate GLYCOGEN SYNTHASE. Glycogen synthase kinases along with CA(2+)-CALMODULIN DEPENDENT PROTEIN KINASES and CYCLIC AMP-DEPENDENT PROTEIN KINASES regulate glycogen synthase activity.
Muscle, Skeletal
Glucagon
A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal GLUCAGON-LIKE PEPTIDES. Glucagon is secreted by PANCREATIC ALPHA CELLS and plays an important role in regulation of BLOOD GLUCOSE concentration, ketone metabolism, and several other biochemical and physiological processes. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1511)
Pentosyltransferases
Uridine Diphosphate Glucose
A key intermediate in carbohydrate metabolism. Serves as a precursor of glycogen, can be metabolized into UDPgalactose and UDPglucuronic acid which can then be incorporated into polysaccharides as galactose and glucuronic acid. Also serves as a precursor of sucrose lipopolysaccharides, and glycosphingolipids.
Phosphoprotein Phosphatases
Protein Phosphatase 1
A eukayrotic protein serine-threonine phosphatase subtype that dephosphorylates a wide variety of cellular proteins. The enzyme is comprised of a catalytic subunit and regulatory subunit. Several isoforms of the protein phosphatase catalytic subunit exist due to the presence of multiple genes and the alternative splicing of their mRNAs. A large number of proteins have been shown to act as regulatory subunits for this enzyme. Many of the regulatory subunits have additional cellular functions.
Allosteric Site
Starch Phosphorylase
An enzyme of the PHOSPHORYLASES family that catalyzes the degradation of starch, a mixture of unbranched AMYLOSE and branched AMYLOPECTIN compounds. This phosphorylase from plants is the counterpart of GLYCOGEN PHOSPHORYLASE in animals that catalyzes the reaction of inorganic phosphate on the terminal alpha-1,4-glycosidic bond at the non-reducing end of glucans resulting in the release of glucose-1-phosphate.
Acetylcarnitine
Lactic Acid
Cyclic AMP
An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.
Glycolysis
A metabolic process that converts GLUCOSE into two molecules of PYRUVIC ACID through a series of enzymatic reactions. Energy generated by this process is conserved in two molecules of ATP. Glycolysis is the universal catabolic pathway for glucose, free glucose, or glucose derived from complex CARBOHYDRATES, such as GLYCOGEN and STARCH.
Allosteric Regulation
The modification of the reactivity of ENZYMES by the binding of effectors to sites (ALLOSTERIC SITES) on the enzymes other than the substrate BINDING SITES.
Rats, Inbred Strains
Epinephrine
The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.
Gluconeogenesis
Biosynthesis of GLUCOSE from nonhexose or non-carbohydrate precursors, such as LACTATE; PYRUVATE; ALANINE; and GLYCEROL.
Phenylbutyrates
Amides
Organic compounds containing the -CO-NH2 radical. Amides are derived from acids by replacement of -OH by -NH2 or from ammonia by the replacement of H by an acyl group. (From Grant & Hackh's Chemical Dictionary, 5th ed)
Indoles
Caffeine
A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.
Pyridoxal
The 4-carboxyaldehyde form of VITAMIN B 6 which is converted to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid.
Enzyme Inhibitors
Lactates
Salts or esters of LACTIC ACID containing the general formula CH3CHOHCOOR.
Binding Sites
Phosphorylation
Quinolinic Acids
Rats, Wistar
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Insulin
A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).
Arabinose
Myxomycetes
Vasopressins
Antidiuretic hormones released by the NEUROHYPOPHYSIS of all vertebrates (structure varies with species) to regulate water balance and OSMOLARITY. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a CYSTINE. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the KIDNEY COLLECTING DUCTS to increase water reabsorption, increase blood volume and blood pressure.
Isoenzymes
Protein Conformation
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
Protein Kinases
Adenosine Triphosphate
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
Protein Binding
Substrate Specificity
Pyridoxine
The 4-methanol form of VITAMIN B 6 which is converted to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990).
Fructosephosphates
Fructosephosphates are organic compounds resulting from the combination of fructose with a phosphate group, playing crucial roles in various metabolic processes, particularly within carbohydrate metabolism.
Amino Acid Sequence
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Models, Molecular
Glucose-6-Phosphatase
Glycogen-Synthase-D Phosphatase
An enzyme that catalyzes the conversion of phosphorylated, inactive glycogen synthase D to active dephosphoglycogen synthase I. EC 3.1.3.42.
Calcium
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Glycogen Storage Disease Type I
An autosomal recessive disease in which gene expression of glucose-6-phosphatase is absent, resulting in hypoglycemia due to lack of glucose production. Accumulation of glycogen in liver and kidney leads to organomegaly, particularly massive hepatomegaly. Increased concentrations of lactic acid and hyperlipidemia appear in the plasma. Clinical gout often appears in early childhood.
Hydrogen-Ion Concentration
Peptones
Derived proteins or mixtures of cleavage products produced by the partial hydrolysis of a native protein either by an acid or by an enzyme. Peptones are readily soluble in water, and are not precipitable by heat, by alkalis, or by saturation with ammonium sulfate. (Dorland, 28th ed)
Catalysis
Magnetic Resonance Spectroscopy
Crystallography, X-Ray
The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Hexokinase
An enzyme that catalyzes the conversion of ATP and a D-hexose to ADP and a D-hexose 6-phosphate. D-Glucose, D-mannose, D-fructose, sorbitol, and D-glucosamine can act as acceptors; ITP and dATP can act as donors. The liver isoenzyme has sometimes been called glucokinase. (From Enzyme Nomenclature, 1992) EC 2.7.1.1.
Phosphofructokinase-1
An allosteric enzyme that regulates glycolysis by catalyzing the transfer of a phosphate group from ATP to fructose-6-phosphate to yield fructose-1,6-bisphosphate. D-tagatose- 6-phosphate and sedoheptulose-7-phosphate also are acceptors. UTP, CTP, and ITP also are donors. In human phosphofructokinase-1, three types of subunits have been identified. They are PHOSPHOFRUCTOKINASE-1, MUSCLE TYPE; PHOSPHOFRUCTOKINASE-1, LIVER TYPE; and PHOSPHOFRUCTOKINASE-1, TYPE C; found in platelets, brain, and other tissues.
Ribonucleotides
Macromolecular Substances
Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
Pyruvate Dehydrogenase Complex
A multienzyme complex responsible for the formation of ACETYL COENZYME A from pyruvate. The enzyme components are PYRUVATE DEHYDROGENASE (LIPOAMIDE); dihydrolipoamide acetyltransferase; and LIPOAMIDE DEHYDROGENASE. Pyruvate dehydrogenase complex is subject to three types of control: inhibited by acetyl-CoA and NADH; influenced by the energy state of the cell; and inhibited when a specific serine residue in the pyruvate decarboxylase is phosphorylated by ATP. PYRUVATE DEHYDROGENASE (LIPOAMIDE)-PHOSPHATASE catalyzes reactivation of the complex. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed)
Adenosine Diphosphate
Pyruvate Kinase
ATP:pyruvate 2-O-phosphotransferase. A phosphotransferase that catalyzes reversibly the phosphorylation of pyruvate to phosphoenolpyruvate in the presence of ATP. It has four isozymes (L, R, M1, and M2). Deficiency of the enzyme results in hemolytic anemia. EC 2.7.1.40.
Chemistry
Chemical Phenomena
Inosine
A purine nucleoside that has hypoxanthine linked by the N9 nitrogen to the C1 carbon of ribose. It is an intermediate in the degradation of purines and purine nucleosides to uric acid and in pathways of purine salvage. It also occurs in the anticodon of certain transfer RNA molecules. (Dorland, 28th ed)
Carbohydrate Metabolism
Hypoglycemic Agents
Substances which lower blood glucose levels.
Cells, Cultured
Stellate Ganglion
Muscle Proteins
X-Ray Diffraction
The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Hepatocytes
The main structural component of the LIVER. They are specialized EPITHELIAL CELLS that are organized into interconnected plates called lobules.
Base Sequence
Pyruvic Acid
Adenine Nucleotides
Adenine nucleotides are molecules that consist of an adenine base attached to a ribose sugar and one, two, or three phosphate groups, including adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP), which play crucial roles in energy transfer and signaling processes within cells.
Glycogen Storage Disease Type II
An autosomal recessively inherited glycogen storage disease caused by GLUCAN 1,4-ALPHA-GLUCOSIDASE deficiency. Large amounts of GLYCOGEN accumulate in the LYSOSOMES of skeletal muscle (MUSCLE, SKELETAL); HEART; LIVER; SPINAL CORD; and BRAIN. Three forms have been described: infantile, childhood, and adult. The infantile form is fatal in infancy and presents with hypotonia and a hypertrophic cardiomyopathy (CARDIOMYOPATHY, HYPERTROPHIC). The childhood form usually presents in the second year of life with proximal weakness and respiratory symptoms. The adult form consists of a slowly progressive proximal myopathy. (From Muscle Nerve 1995;3:S61-9; Menkes, Textbook of Child Neurology, 5th ed, pp73-4)
Energy Metabolism
Structure-Activity Relationship
Sympatholytics
Drugs that inhibit the actions of the sympathetic nervous system by any mechanism. The most common of these are the ADRENERGIC ANTAGONISTS and drugs that deplete norepinephrine or reduce the release of transmitters from adrenergic postganglionic terminals (see ADRENERGIC AGENTS). Drugs that act in the central nervous system to reduce sympathetic activity (e.g., centrally acting alpha-2 adrenergic agonists, see ADRENERGIC ALPHA-AGONISTS) are included here.
Hormones
Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects.
Catalytic Domain
1,4-alpha-Glucan Branching Enzyme
In glycogen or amylopectin synthesis, the enzyme that catalyzes the transfer of a segment of a 1,4-alpha-glucan chain to a primary hydroxy group in a similar glucan chain. EC 2.4.1.18.
Okadaic Acid
A specific inhibitor of phosphoserine/threonine protein phosphatase 1 and 2a. It is also a potent tumor promoter. (Thromb Res 1992;67(4):345-54 & Cancer Res 1993;53(2):239-41)
Dose-Response Relationship, Drug
Hyperglycemia
Abnormally high BLOOD GLUCOSE level.
Phenylephrine
Myocardium
Spectrophotometry, Ultraviolet
Glycogen Storage Disease Type III
An autosomal recessive metabolic disorder due to deficient expression of amylo-1,6-glucosidase (one part of the glycogen debranching enzyme system). The clinical course of the disease is similar to that of glycogen storage disease type I, but milder. Massive hepatomegaly, which is present in young children, diminishes and occasionally disappears with age. Levels of glycogen with short outer branches are elevated in muscle, liver, and erythrocytes. Six subgroups have been identified, with subgroups Type IIIa and Type IIIb being the most prevalent.
Muscle Contraction
A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
Isoproterenol
Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.
Molecular Structure
Mutation
Floxuridine
An antineoplastic antimetabolite that is metabolized to fluorouracil when administered by rapid injection; when administered by slow, continuous, intra-arterial infusion, it is converted to floxuridine monophosphate. It has been used to treat hepatic metastases of gastrointestinal adenocarcinomas and for palliation in malignant neoplasms of the liver and gastrointestinal tract.